Pediatric sonography changes with the patient’s size, age and stage of development. A structure that is easy to see in a newborn may require another window in an older child, while a normal developmental feature can resemble disease if its location is overlooked. This guide builds from image acquisition and Doppler technique to organ systems, the neonatal brain and spine, musculoskeletal structures, and the thorax. Each topic asks you to connect an observed pattern with the next useful imaging step: confirm it in another plane, adjust the settings, assess related anatomy, or communicate a time-sensitive concern. The sonographer’s work is to acquire and describe dependable findings, recognize limitations, and escalate appropriately within the clinical team.
Pediatric examination methods, physics and clinical practice
1. Choose the imaging approach
Start with the depth and size of the target, then choose a probe that shows the entire structure with useful detail. Higher frequencies produce shorter wavelengths and better spatial resolution, but their sound attenuates sooner. A high-frequency linear probe suits a shallow neck mass because its near-field detail and rectangular image help define margins. A lower-frequency curved probe penetrates farther and provides a wider view at depth. Footprint matters too: a small probe can fit between ribs or under a small chin, while a broader probe may cover more abdomen in one sweep. Change the acoustic window or gently reposition the child before assuming a structure is absent. Record which portions remain unseen. The broader RDMS study guide provides context for the sonographer's role.
Worked example: An infant has a palpable neck lump close to the skin. Begin with a high-frequency linear probe and scan in two planes to show its superficial margins. Its deep edge disappears beyond the useful image depth, so switch to a lower frequency or curved probe and rescan. The second view establishes its full extent; the first preserves finer superficial detail.
Watch the distinction: The highest available frequency is not automatically best. If attenuation hides the deep margin, a sharper image of only part of the lump cannot establish its size or origin.
2. Build a readable gray-scale image
Set depth first so the target and a little tissue beyond it fill the display. Excess depth wastes pixels and makes small features harder to judge. Position the focal zone at or just behind the structure of interest, where lateral resolution is strongest. Adjust overall gain until fluid remains dark and soft-tissue boundaries are visible without widespread speckle saturation. Then use time-gain compensation to correct a depth-dependent brightness difference; it should not manufacture uniform tissue where a real difference exists. Dynamic range controls how many shades of gray appear: a broad range gives a softer image, while a narrow range increases contrast but may erase subtle texture. After each adjustment, reassess reference tissues at similar depths. Acquisition settings must be settled before calling a cortex unusually bright or dark.
Worked example: A child's kidney occupies only one third of the screen, and its deep cortex appears dark. Reduce depth until the kidney fills most of the image while retaining its posterior border. Put the focus near renal depth, normalize overall gain, and raise deep time-gain compensation modestly. Compare both cortices again; the initial darkness may have been attenuation rather than disease.
Watch the distinction: Increasing overall gain to brighten a deep cortex also brightens the near cortex and collecting system. Correct the depth-dependent loss before interpreting renal echogenicity.
3. Test an apparent lesion
An apparent lesion should survive changes in plane and insonation angle. Tendons are highly angle dependent: when the beam is oblique to their fibers, reflected sound misses the probe and normal fibers look dark. Tilt until the beam is perpendicular and scan in a second plane. Reverberation produces repeated echoes at regular spacing behind strong reflectors; a true structure retains a consistent location when the probe moves. Clean posterior shadowing suggests marked attenuation or reflection, whereas increased brightness deep to fluid is posterior enhancement. Neither artifact alone identifies a lesion. Partial-volume effects arise when a thick slice averages adjacent structures, especially near curved margins. Use a thinner beam, alternate window, and orthogonal views to decide whether a finding has stable anatomy. Document persistent findings and relevant artifacts separately.
Worked example: A short segment of an ankle tendon looks dark on a longitudinal view. When the probe is tilted, the fibers become uniformly bright and continuous. The transverse view shows no gap or retracted ends. Angle-dependent recovery favors anisotropy. A genuine tear would leave a reproducible defect or disrupted fibers in appropriate orthogonal views.
Watch the distinction: A dark tendon segment is not proof of a tear. The tendon may be normal but insonated obliquely; test its angle response before describing structural disruption.
4. Find slow blood flow
Small pediatric vessels may carry velocities below a default color display setting. First confirm that the color box covers the tissue and that the probe is stable. Reduce the velocity scale, lower the wall filter so slow signals are retained, and increase color gain until background noise begins, then back off slightly. A smaller color box and suitable frequency can improve frame rate and sensitivity. Compare the opposite side using the same settings, and sample a known vessel to confirm the system detects flow. Power Doppler may reveal weak flow but has limited directional information and remains motion sensitive. Spectral Doppler can confirm a signal when color is equivocal, provided the sample volume is correctly placed. Absence of detectable flow after optimization is a concerning observation, not proof of zero perfusion.
Worked example: A neonatal testis has no color signal at a high scale, but the opposite testis is also blank. Lower the scale and wall filter, raise gain to just below the noise level, and hold a small color box steady. Flow now appears on the opposite side but remains markedly reduced on the symptomatic side. Document the optimized comparison and escalate the asymmetry.
Watch the distinction: An empty color box does not establish absent perfusion. A high scale, aggressive wall filter, low gain, motion, or an unsuitable insonation angle can erase slow flow.
5. Correct the Doppler angle
Spectral Doppler detects the component of blood velocity along the ultrasound beam. If flow and beam form angle θ, the measured component equals true velocity times cos(θ); therefore true velocity equals measured component divided by cos(θ). Align the angle cursor with the vessel's flow direction, not merely its wall if the stream bends. Use a long, straight segment and keep the angle as small as practical. As θ approaches 90 degrees, cosine approaches zero, so even a small angle error can cause a large velocity error. At 60 degrees, cosine is 0.5; at 70 degrees, it is about 0.342. The same measured component would yield substantially different results. The related sonography physics guide reinforces the beam and flow relationship.
Worked example: A hypothetical beam-axis velocity is 0.50 m/s at a true angle of 60 degrees. Because cos(60°) = 0.50, corrected velocity is 0.50 ÷ 0.50 = 1.00 m/s. If the operator incorrectly enters 70 degrees, the displayed correction becomes 0.50 ÷ 0.342, about 1.46 m/s. The difference reflects angle error, not faster blood.
Watch the distinction: Angle correction is not a harmless display setting. Placing the cursor along the wrong direction can overstate velocity, especially when the chosen angle is steep.
6. Prepare the child and examination
Before scanning, match the child's identifiers to the request and verify the clinical question, relevant history, and preparation. Preparation affects interpretation: feeding, voiding, or a full bladder can change the anatomy visible during a targeted study. Explain the next action in words appropriate to the child's age, allowing a caregiver to provide comfort and useful history without substituting for identity checks. Position gently and use warm gel when available; distress and movement can obscure transient events that the examination needs to observe. For a dynamic study, watch during quiet intervals and repeat observations if motion interrupts them. Record preparation or cooperation that limits the study. The ARDMS credential identifies a sonography profession, while the examination record must still describe what this particular child could and could not tolerate.
Worked example: A distressed toddler is referred for a pyloric study. Confirm identity, the request, recent feeding, and any preparation instructions. Invite the caregiver to settle the child while you position the probe gently over the stomach. Observe several calm intervals for channel opening and passage. If crying interrupts the view, repeat the observation and record the limitation rather than labeling the momentary absence of passage as obstruction.
Watch the distinction: A single moment without visible gastric passage is not evidence of persistent obstruction when crying or movement obscures the pylorus. Settle and observe the child dynamically.
7. Use output and time prudently
Use enough acoustic output to answer the question, and avoid unnecessary dwell time over one small target. Thermal and mechanical indices are displayed estimates that help monitor exposure; they are not substitutes for choosing appropriate settings and moving efficiently. Doppler modes may use greater output than a routine gray-scale survey, so obtain the needed sample, then return to the lower-output mode when appropriate. Keep the transducer moving while reviewing images and avoid repeating measurements that are already adequate. Infection control includes cleaning probes and shared surfaces according to their use and maintaining barriers when required. Ergonomics protects both examiner and child: bring the patient close, support the scanning arm, and avoid sustained wrist twist or pressure. The American Institute of Ultrasound in Medicine is a professional ultrasound organization with practice resources.
Worked example: A neonatal scan runs long because several Doppler vessels need assessment. The sonographer selects the necessary vessel, acquires a stable spectrum promptly, and then leaves Doppler mode. While reviewing saved images, the probe is lifted rather than held motionless on the infant. Probe cleaning and workstation position are checked before the next patient. The examination remains complete without avoidable dwell.
Watch the distinction: A low displayed index does not justify prolonged stationary scanning. Output, exposure time, mode, and the need for each acquisition must be considered together.
8. Report and escalate findings
A useful sonography record lets another clinician understand where a finding came from and how certain the observation is. Save representative images in two planes with orientation and landmarks. State how a measurement was made, including caliper boundaries, and describe flow settings when detectability matters. Document missing anatomy, bowel gas, motion, or limited windows rather than silently treating unseen structures as normal. Distinguish an observation, such as a whirlpool appearance, from a final etiologic diagnosis. Compare with prior images only when the same landmark and method permit comparison. If a finding could represent a time-sensitive condition, communicate the concerning observation promptly through the clinical pathway and record whom you contacted and when. The sonographer supplies accurate evidence and escalation; the responsible clinician integrates it with the broader case.
Worked example: A vomiting child's scan shows a whirlpool pattern near the mesenteric vessels, but bowel gas hides part of the duodenal course. Save transverse and longitudinal images, label the vessel relationships, and state the obscured segment. Promptly relay the possible twisting pattern and study limit through the clinical pathway. Record the recipient and time. Do not present the limited scan as a definitive diagnosis.
Watch the distinction: A technically limited study is not a negative study. If an urgent pattern is visible despite incomplete anatomy, document both the pattern and the limitation and communicate promptly.
Abdomen and gastrointestinal tract
9. Map abdominal orientation
Begin an abdominal survey by locating the liver, spleen, stomach, aorta, and inferior vena cava, then map their relationships. Situs describes the overall organ arrangement; one displaced organ is insufficient to infer a different situs pattern. A mass may push an otherwise normal spleen downward, while congenital variants can alter organ and vessel positions together. Trace vessels into the organ to identify it and search for the expected structure in its usual location. Scan broadly enough to detect associated abnormalities, especially when a congenital pattern is suspected. Respiratory motion, patient rotation, and a narrow field can make structures appear unexpectedly positioned, so confirm in orthogonal planes. Record the relationship that supports your interpretation rather than relying on a single screen orientation. A clear map helps guide later targeted views.
Worked example: A spleen appears unusually low on a child's left side. The liver remains right-sided, the stomach is left-sided, and the aorta and vena cava retain their expected relationships. Trace splenic vessels to the low organ and sweep above it for a displacing mass. These findings favor isolated displacement or position variation; they do not establish altered situs.
Watch the distinction: Calling abnormal situs from one low spleen skips the arrangement of the other organs. Check stomach, liver, and major vessels before assigning a global orientation pattern.
10. Characterize liver and spleen
Pediatric organ size must be compared with a reference appropriate to age or body size and measured in the same plane used by that reference. Record the longest reproducible splenic or hepatic dimension, but also assess contour, texture, and associated vessels. A focal lesion should be described by location, dimensions, cystic or solid components, internal echoes, margins, and vascularity. A simple fluid appearance differs from a solid vascular mass, yet ultrasound alone rarely identifies histology. A splenic-hilar nodule matching splenic echotexture and vascular supply may represent an accessory spleen; distinguish it from a separate mass by tracing its relationship to the spleen. Clinical history can change the differential, including infection, trauma, or vascular disease. The related abdomen study guide offers broader abdominal context.
Worked example: A child's spleen measures 11 cm in its maximal plane. A hypothetical reference for that child's body size is 8–10 cm, so 11 cm exceeds its upper value by 1 cm and supports enlargement under that reference. A separate round hilar nodule matches splenic texture and shows similar vascularity, favoring an accessory spleen appearance. Describe both findings without assigning the nodule's histology.
Watch the distinction: A measurement cannot be judged against an adult reference or an unrelated pediatric age group. State the supplied comparison and keep size separate from lesion characterization.
11. Trace hepatic blood flow
Identify the portal vein by its course into the liver and echogenic walls, then use color and spectral Doppler to establish flow direction relative to the liver. Hepatopetal flow travels toward it; hepatofugal flow travels away. Set the color map and probe orientation deliberately because screen color alone does not specify anatomical direction. Sample more than one segment when flow is weak or changes with respiration. Hepatic veins drain toward the inferior vena cava and show waveform variation influenced by cardiac and respiratory cycles. A serpiginous vessel near the hilum may represent a collateral, but it should be traced rather than assumed. Reversed portal flow plus collateral vessels can suggest portal hypertension; abnormal hepatic venous drainage can raise concern for obstruction. State the observed directions and waveforms before offering a sonographic differential.
Worked example: On repeated views, the main portal vein carries flow away from the liver, and a serpiginous hilar vessel has demonstrable flow. Confirm the portal vein's course and color-map orientation, then obtain a spectrum at suitable settings. Record hepatofugal portal flow and the collateral-appearing vessel. Together they are concerning for portal hypertension, although the scan does not establish its cause.
Watch the distinction: Red and blue do not mean hepatic inflow and outflow by themselves. Direction depends on probe orientation and the color map; trace the vessel anatomically before interpreting it.
12. Assess the biliary tree
Neonatal cholestasis requires a structured look at the gallbladder, intrahepatic and extrahepatic ducts, porta hepatis, and adjacent vessels. An unusually small or irregular gallbladder and echogenic tissue at the porta hepatis can raise concern for biliary atresia, but the appearance of a gallbladder or nondilated ducts cannot reliably exclude it. Preparation and recent feeding affect gallbladder size, so record the context. For cystic biliary dilatation, follow the fluid space along the duct in two planes and demonstrate a communicating channel where possible. A choledochal abnormality connects to the biliary tree; an adjacent hepatic, enteric, or pancreatic cyst may merely touch it. Sludge can move or layer, while stones may produce a discrete echogenic focus with shadowing. Describe the anatomy and degree of confidence, then communicate concerning neonatal findings promptly.
Worked example: An infant with cholestasis has an irregular gallbladder and echogenic porta hepatis, increasing concern for biliary atresia without proving it. A separate cystic structure is traced into a dilated bile duct in two planes, which supports a choledochal abnormality. Record the duct connection and gallbladder preparation status, and communicate the combined findings for clinical evaluation.
Watch the distinction: A visible gallbladder does not rule out biliary atresia. Its morphology, the porta hepatis, duct anatomy, and clinical cholestasis must be considered together.
13. Survey pancreatic and splenic injury
After abdominal trauma or suspected inflammation, examine pancreatic size, contour, echogenicity, duct, and surrounding fluid, then survey the spleen and nearby spaces. A swollen pancreas or peripancreatic fluid may support injury or inflammation, but appearances can be subtle early and bowel gas can hide much of the gland. For the spleen, look for a parenchymal defect, subcapsular collection, free fluid, and altered contour. Complex perisplenic fluid is important even when no laceration is visible. Sonography samples accessible anatomy and cannot reliably exclude deep pancreatic or splenic injury from an apparently normal image. Record which portion of each organ was seen and where fluid lies. Escalate concerning findings in the clinical context; the treatment decision depends on the full trauma or inflammatory assessment.
Worked example: Following a fall, a child has complex fluid around the spleen. No splenic cleft is visible, and bowel gas obscures the pancreatic body and tail. Save the fluid and splenic views and document the limited pancreatic assessment. The fluid raises concern for injury, while the absence of a visible defect does not exclude a splenic laceration or pancreatic injury.
Watch the distinction: A clean-looking splenic surface cannot cancel the significance of perisplenic complex fluid. Likewise, a pancreas hidden by gas has not been shown to be normal.
14. Observe the pylorus dynamically
A pyloric examination is a dynamic assessment of muscle shape and gastric passage. Obtain a true transverse view to measure a single muscular wall from outer margin to inner mucosal boundary, avoiding inclusion of the mucosa. Use a longitudinal view to measure channel length along its axis. An oblique slice can exaggerate either dimension. Watch the channel through repeated contractions, noting whether it opens and whether gastric contents pass. Pylorospasm may temporarily thicken or narrow the muscle but relaxes during observation; persistent fixed narrowing and failed passage are more concerning for obstruction. Interpret dimensions against the age-appropriate criteria supplied in the case, with the observed behavior carrying independent weight. If the child moves or the stomach is poorly visualized, record that limit rather than forcing a measurement.
Worked example: Under hypothetical case criteria, concern requires muscle thickness above 3.0 mm plus persistent nonopening. One transverse measurement is 3.4 mm, but repeated views show thickness falling to 2.2 mm as the channel opens and contents pass. Because the narrowing resolves and passage occurs, the case favors pylorospasm under those criteria rather than persistent obstruction.
Watch the distinction: One thick measurement does not establish fixed pyloric obstruction. An oblique plane or transient contraction can exaggerate thickness; repeat correctly oriented measurements while observing passage.
15. Recognize bowel twisting and telescoping
Twisting and telescoping create different sonographic patterns and call for a careful bowel survey. In possible malrotation with volvulus, trace the duodenal course where visible and assess whether mesenteric vessels and bowel wrap in a whirlpool pattern. Superior mesenteric vessel orientation alone is variable and cannot establish or exclude malrotation. Intussusception appears as concentric bowel layers in cross section and a bowel-within-bowel structure longitudinally, often carrying mesenteric fat and nodes into the receiving segment. After identifying it, assess length and location, mural perfusion, trapped fluid, free fluid, and any lead point. Reduced flow or trapped fluid raises concern about bowel viability but does not independently prove necrosis. Document the pattern and limitations, and promptly communicate findings that could require urgent clinical action.
Worked example: A child has a concentric bowel mass that becomes a bowel-within-bowel structure longitudinally. Mesenteric fat lies inside it, fluid is trapped between layers, and mural Doppler flow is reduced after settings are optimized. These findings support intussusception with concerning viability features. Record location and accessible extent, then communicate promptly; the scan does not by itself establish irreversible ischemia.
Watch the distinction: Reversed mesenteric vessel positions alone do not diagnose volvulus, and a target pattern alone does not assess bowel viability. Trace anatomy and examine perfusion and fluid.
16. Assess inflamed bowel
Use graded compression to move gas and identify the appendix from its cecal origin to its blind tip. Measure its outer-wall-to-outer-wall diameter in a true transverse plane, then assess compressibility, wall structure, Doppler flow, adjacent echogenic fat, and fluid. A partially seen appendix leaves uncertainty about its unseen segment. When the appendix is not visualized, secondary inflammation can still make the study concerning; nonvisualization is a reportable limit rather than a negative result. Broader bowel assessment considers wall thickness, layering, peristalsis, perfusion, mesentery, and peritoneal fluid. In an ill neonate, pneumatosis, portal venous gas, complex fluid, or poor bowel-wall flow is especially concerning. Describe observed features and distribute them by location; sonography does not independently settle the cause of diffuse bowel disease.
Worked example: A child's appendix cannot be traced despite graded compression. At the point of maximal tenderness, the fat is focally echogenic and a small complex fluid pocket is present. Report that the appendix evaluation is nondiagnostic, with concerning secondary inflammatory findings. Do not call the examination negative; these findings need timely clinical integration even without a measured appendix.
Watch the distinction: A nonvisualized appendix is not the same as a normal appendix. Secondary fat change or complex fluid can remain clinically significant when the appendix itself is hidden.
Genitourinary tract, adrenal glands and pelvis
17. Measure the pediatric kidney
Measure renal length in the true maximal longitudinal plane, from upper to lower pole without foreshortening. Rotate and sweep until both poles are clearly shown; an off-axis measurement tends to underestimate length. Compare the result with a pediatric interval matched to the child's size or age as specified. Assess cortical thickness, echogenicity, corticomedullary differentiation, and collecting-system appearance separately from length. Neonatal medullary pyramids are normally relatively hypoechoic and may look like multiple small cysts. Their regular radial distribution within preserved cortex, bilateral symmetry, and lack of mass effect support normal pyramids. A true cyst is a discrete fluid space with its own contour and often posterior enhancement. Document any difference between kidneys and the measurement plane, because serial change is meaningful only when acquisition is comparable.
Worked example: A kidney measures 5.8 cm with both poles shown in its maximal long axis. The hypothetical reference interval supplied for this child is 5.0–6.2 cm, so 5.8 cm lies within it. Multiple symmetric dark areas align with medullary pyramids and the surrounding cortex is preserved. Their distribution favors neonatal anatomy rather than multiple separate renal cysts.
Watch the distinction: A short off-axis renal image can create a falsely small length. Also, symmetric neonatal pyramids should not be labeled cysts without identifying discrete cyst walls and distribution.
18. Map urinary dilatation
Determine whether a fluid space is part of the collecting system by tracing its connection to the renal pelvis and calyces in more than one plane. Pelvicalyceal dilatation extends into calyces and may accompany cortical thinning, hydroureter, or bladder abnormalities. An extrarenal pelvis can project beyond the hilum while calyces remain nondilated and parenchyma preserved. Parapelvic cysts may sit near the pelvis but do not join the collecting system. A full bladder or recent hydration can increase visible pelvic fullness, so record bladder state and repeat an indicated view after voiding when feasible. Survey ureters and bladder because upstream and downstream findings clarify the pattern. Describe anatomy and change over time without equating dilatation with functional obstruction; impaired drainage requires clinical and, when indicated, other functional evidence.
Worked example: A central renal fluid space extends just outside the hilum. Sweeps show no dilated calyces, the cortex remains thick, and no hydroureter is visible. The pattern favors an extrarenal pelvis. Document its dimensions, both kidneys, ureters, and bladder filling. If the bladder is very full, note that state before comparing pelvic fullness with another scan.
Watch the distinction: Pelvic fluid alone does not prove obstruction. First establish whether calyces, ureter, parenchyma, and bladder show associated changes, and account for bladder filling.
19. Trace congenital urinary anatomy
When a kidney is missing from its expected fossa, search the pelvis, lower abdomen, and opposite side before calling agenesis. Ectopic kidneys may have unusual rotation and vessels arising at a different level. Fusion can place renal tissue across the midline; tracing cortex and collecting systems clarifies whether two renal units are joined. A duplex system may show separate upper and lower collecting systems, sometimes with a dilated ureter or a ureterocele projecting into the bladder. Multicystic dysplasia produces multiple noncommunicating cysts replacing much of an abnormal renal unit, unlike connected calyceal dilatation. Once an anomaly is identified, assess the opposite kidney, ureters, and bladder for associated changes. Describe demonstrated anatomy rather than assuming a missing organ, and do not infer functional obstruction merely from collecting-system fullness.
Worked example: No kidney is visible in the left renal fossa. A smaller renal-shaped organ is found in the pelvis, with its own collecting system and a vessel entering from a lower level. This supports pelvic renal ectopia rather than agenesis. Survey the right kidney, both ureteral courses where visible, and bladder, and document the ectopic organ's location and rotation.
Watch the distinction: An empty renal fossa does not establish agenesis. An ectopic or crossed kidney may lie elsewhere, so complete the search and trace its vessels and collecting system.
20. Separate renal deposits and masses
Locate bright renal echoes before naming them. Stones generally lie in the collecting system and may produce discrete shadowing or a color twinkle artifact; very small stones may lack obvious shadowing. Nephrocalcinosis follows the medullary pyramids or cortex as a more distributed pattern, sometimes bilaterally. Assess the collecting system for dilatation and the parenchyma for altered texture. Infection-related change can be diffuse or focal, but a normal scan cannot exclude infection. A simple cyst has fluid features and no internal vascularity; a complex cyst or solid lesion needs detailed description of septa, solid parts, and flow. For a solid renal mass, identify its renal origin, measure three dimensions, and inspect the renal vein and inferior vena cava for visible extension. Ultrasound characterizes anatomy; it does not assign histology.
Worked example: Both kidneys contain bright foci following the medullary pyramids. No discrete collecting-system focus or convincing shadow is seen, and the calyces are not dilated. This distribution favors medullary nephrocalcinosis over isolated stones. Record whether the pattern is bilateral, describe cortical texture and any dilatation, and avoid claiming that every small stone has been excluded.
Watch the distinction: All bright renal foci are not stones. Their position and distribution matter; medullary echogenicity following pyramids suggests a different process from a discrete collecting-system deposit.
21. Evaluate bladder emptying and outlet
Scan the bladder in two planes at a documented degree of filling. A nearly empty bladder can look thick walled because its lining folds; marked distention can make a wall abnormality less conspicuous. Describe focal or diffuse wall change, debris, and any ureterocele or dilated distal ureter. Ureteric jets show intermittent urine entry, so failure to see one during a short observation does not establish obstruction. When a residual is requested, estimate volume immediately before and after voiding with the same measurement method, and record whether the child could void normally. Compare bladder findings with the kidneys and ureters. Hydroureter and a distended bladder can raise concern for an outlet problem, but dilatation also depends on filling, reflux, and other causes. An ARDMS sonographer reports the observed pattern and its limits for clinical assessment.
Worked example: A child has a distended bladder and bilateral hydroureter. Estimated bladder volume is 120 mL before voiding and 35 mL immediately afterward. The residual is 35 mL; 35 ÷ 120 × 100 is about 29% of the initial volume. Record both volumes, the voiding conditions, and the hydroureter. This combination warrants further assessment but does not, by itself, prove functional outlet obstruction.
Watch the distinction: Calling hydroureter proof of outlet obstruction skips the bladder and voiding context. Likewise, an unseen ureteric jet during brief sampling is not equivalent to absent urine flow.
22. Examine neonatal adrenal lesions
Locate a neonatal suprarenal finding in transverse and longitudinal planes before naming its origin. Show the upper renal pole separately and look for the adrenal gland's relationship to the kidney, aorta, and nearby vessels. A hemorrhage can change from echogenic and solid appearing to mixed and then cystic as blood products evolve; decreasing size over serial examinations strengthens that interpretation. Record dimensions in matching planes so apparent change is not caused by a different section. Color Doppler helps distinguish internal tissue flow from flow in displaced adjacent vessels, but weak or absent signal is sensitive to settings and does not settle the diagnosis. A persistent or enlarging solid component, especially one with internal vascularity, changes the concern and merits prompt clinical review. The sonographer describes location and evolution rather than assigning a tumor type from appearance alone.
Worked example: A newborn has a suprarenal mass clearly separate from the kidney. On comparable follow-up views, it is smaller and more cystic, and optimized color Doppler shows no internal flow. The location and evolution are compatible with resolving adrenal hemorrhage. If a later scan instead shows growth and a vascular solid nodule, document the change and communicate it for further assessment.
Watch the distinction: An avascular suprarenal mass is not automatically hemorrhage. Flow may be below Doppler sensitivity, and a single appearance cannot replace documented interval change and anatomic localization.
23. Assess the pediatric pelvis
Interpret the pediatric uterus and ovaries with the child's age and pubertal stage in mind. Size, follicle visibility, and uterine proportions change during development, so a finding should be measured and described before an adult label is applied. For suspected torsion, survey both ovaries for asymmetry, edema, peripheral follicles, free fluid, and the position of any associated cyst or mass. Follow the vascular pedicle when visible; a twisted pedicle is a particularly direct clue. Compare color and spectral flow using settings capable of detecting slow flow. Preserved arterial signal cannot exclude torsion because the ovary has more than one arterial supply and venous outflow may be affected first or intermittently. Combine morphology, pedicle appearance, flow, and symptoms, then communicate a concerning pattern promptly without claiming that Doppler alone decides viability.
Worked example: A child with sudden pelvic pain has an enlarged, edematous ovary with peripheral follicles. A coiled pedicle is visible, yet arterial flow remains detectable within the ovary. Enlargement and the twisted pedicle keep torsion high on the sonographic differential despite that flow. Save the pedicle and bilateral comparison views, document the preserved signal accurately, and communicate the concern urgently.
Watch the distinction: A Doppler waveform does not clear a painful ovary. Residual or intermittent arterial inflow can coexist with torsion, so morphology and pedicle findings must remain in the assessment.
24. Compare the testes and inguinal canals
Start a scrotal study by locating both testes, including the inguinal canals if a testis is absent from the scrotum. Compare testicular size, echotexture, epididymides, spermatic cords, and surrounding fluid. In acute pain, seek a twisted cord as well as asymmetric perfusion. Optimize color scale, gain, and wall filter for slow intratesticular flow, then use equivalent settings on both sides; a technical failure can imitate ischemia. Epididymal enlargement and increased flow may favor inflammation, while a simple fluid envelope supports hydrocele. Bowel or omentum entering the canal suggests hernia, and an undescended testis may lie along the normal descent route or elsewhere. These patterns can overlap. A suspected twisted cord or markedly reduced flow needs urgent communication because detectable residual flow does not reliably exclude torsion.
Worked example: An adolescent with abrupt unilateral pain has a coiled spermatic cord. After lowering the color scale and comparing both testes at the same settings, flow on the painful side remains markedly reduced, though a few signals persist. Record cord morphology, bilateral flow, testicular appearance, and any hydrocele. Communicate suspected torsion urgently; the residual signal does not resolve the concern.
Watch the distinction: Comparing testes at different Doppler settings can manufacture an apparent flow difference. Conversely, treating a few color pixels as proof against torsion ignores a twisted cord and incomplete ischemia.
Neonatal and pediatric cranial sonography
25. Acquire the cranial survey
A cranial survey needs repeatable coronal and sagittal sweeps, not isolated images of a suspicious spot. Through the anterior fontanelle, move through frontal lobes, frontal horns, caudothalamic grooves, ventricular bodies, thalami, atria, and posterior regions. Rotate for midline and parasagittal views of the corpus callosum, ventricular margins, periventricular white matter, and extra-axial spaces. Identify landmarks before deciding whether an echogenic focus is inside a ventricle or beside it. The posterior fontanelle can improve views of occipital horns, while a mastoid window helps show the cerebellum, fourth ventricle, and other posterior fossa structures. Window choice depends on age and openness. Document any region that remains obscured. Practicing the ordered landmark sequence in PS practice questions helps link a described finding to its true location.
Worked example: The anterior fontanelle survey shows the frontal horns and ventricular bodies well, but the right occipital horn is obscured. The sonographer adds posterior fontanelle views and confirms both occipital horns in orthogonal planes. A mastoid view then shows the cerebellum and fourth ventricle. The report specifies which structures were demonstrated and any remaining limitation.
Watch the distinction: A clear anterior fontanelle image does not mean the entire brain was surveyed. Posterior horns and fossa structures may need additional windows before an examination can be called complete.
26. Recognize normal cranial variants
Normal intracranial structures can imitate pathology when only one plane is considered. Choroid plexus is normally echogenic and follows a recognizable course within the lateral ventricles, especially toward the atria. Confirm its continuity, position, and symmetry on coronal and sagittal views. Free intraventricular blood may form material in an unexpected location, layer dependently, or alter ventricular outlines, although appearance varies with age of blood. Midline fluid spaces such as the cavum septi pellucidi occupy expected positions between symmetric boundaries; a displaced or irregular cystic structure needs closer mapping. Apparent asymmetry can arise from oblique insonation, so correct the plane before labeling a variant abnormal. Describe what is seen and where. Location and multiplanar relationships provide stronger evidence than brightness or darkness alone.
Worked example: Bright tissue is visible in both lateral ventricles near the atria. On coronal and parasagittal views it remains continuous with the expected choroid plexus course, and there is no separate dependent material or ventricular enlargement. Those relationships favor normal plexus. A separate echogenic deposit outside that course would require documentation as a distinct finding rather than being folded into the variant.
Watch the distinction: Brightness alone does not identify hemorrhage. Choroid plexus is normally bright, and an oblique view can make symmetric structures look unequal; verify their location and continuity first.
27. Describe germinal matrix hemorrhage
The caudothalamic groove is a key landmark because germinal matrix hemorrhage commonly begins there in premature infants. Scan the groove bilaterally in coronal and parasagittal planes, then follow any echogenic material into the ventricular system. Separate a localized groove focus from intraventricular extension, and assess whether ventricular size has changed. Look for associated periventricular parenchymal abnormalities rather than assuming all brightness represents the same process. Serial studies may show changing clot echogenicity and ventricular caliber, so record side, extent, and comparable measurements. A grading label is useful only when its definitions are supplied or established for the case; different descriptions can group ventricular enlargement differently. The sonographer's durable task is an accurate anatomic account that allows the interpreting clinician to apply the stated scheme.
Worked example: A case defines category A as groove-only blood and category B as groove blood extending into a ventricle without enlargement. Echogenic material starts in the left caudothalamic groove and continues into the left lateral ventricle; ventricular size is unchanged and no parenchymal lesion is seen. Under this hypothetical scheme, it is category B. Document each observation as well as the category.
Watch the distinction: Assigning a hemorrhage grade from the groove focus alone can miss ventricular extension. A label is also misleading if its grading scheme and ventricular findings are left unstated.
28. Follow periventricular injury
Periventricular brightness needs a map and a timeline. A unilateral, wedge-shaped echogenic region next to a ventricle with hemorrhage raises concern for periventricular hemorrhagic infarction, a parenchymal process beyond uncomplicated intraventricular clot. More diffuse white matter echogenicity may reflect several causes, including transient changes, so compare its intensity with nearby landmarks, symmetry, distribution, and persistence on serial scans. Later cyst formation provides a different level of concern for white matter injury, including periventricular leukomalacia patterns. Describe whether cavities develop within the prior bright region and whether ventricular shape subsequently changes. Avoid treating every early echogenic area as permanent injury or every ventricular clot as parenchymal infarction. Consistent planes and dates are essential because evolution, rather than one still image, often distinguishes these processes.
Worked example: A premature infant has ventricular blood and a new unilateral wedge-shaped bright area extending into adjacent white matter. On a later comparable scan, the wedge contains small cavities. The asymmetric distribution and cavitation support concern for evolving parenchymal injury, including periventricular hemorrhagic infarction. Brief symmetric brightness that disappears without cysts would carry a different interpretation.
Watch the distinction: Calling all periventricular echogenicity leukomalacia erases important differences. Shape, laterality, association with ventricular blood, persistence, and cystic evolution determine what the finding can support.
29. Track ventricular enlargement
Ventricular measurements become useful only when the same structure is measured at the same landmark, plane, and caliper position each time. Obliquity can enlarge an apparent width, while a different portion of the ventricle can make serial values incomparable. Record the named measurement, side, image plane, and date. Compare size with the rest of the ventricular system: enlargement of lateral ventricles with a relatively unchanged downstream ventricle can suggest a different obstruction pattern from enlargement of all ventricles. Also note clot, mass effect, midline change, and extra-axial spaces. A rising measure is evidence of progression when technique is comparable, but the number alone does not establish the cause or dictate treatment. Repeat a doubtful plane before communicating an apparent interval increase.
Worked example: At one specified ventricular landmark, a baseline scan measures 8 mm and a follow-up scan measures 12 mm. Both images use the same coronal plane and caliper placement. The increase is 12 − 8 = 4 mm, supporting real interval enlargement. The sonographer records the measurement method and checks the other ventricles and any clot before describing the pattern.
Watch the distinction: A larger number on a later report is not automatically progression. Different planes or caliper landmarks can create change, so confirm comparability before interpreting the difference.
30. Survey congenital brain anatomy
Congenital cranial assessment begins with a structural checklist: midline commissures, septum and ventricular configuration, posterior fossa, cerebellar relationship, visible cortical pattern, and any known spinal defect. A missing or poorly seen corpus callosum should be checked in more than one plane and paired with observations about ventricular shape and other midline structures. Posterior fossa abnormalities may require mastoid views because the anterior fontanelle can hide important anatomy. Ultrasound can identify a pattern that warrants further characterization, but limited acoustic windows and developmental stage may prevent full assessment of cortical organization or connections between structures. Document what is visible, what was specifically sought but not demonstrated, and the image limitation. This makes the referral for additional imaging precise without turning an incomplete view into a definitive congenital diagnosis.
Worked example: The corpus callosum is not identified on well-centered sagittal or coronal views, and the lateral ventricles have an unusual configuration. The sonographer records both findings, surveys the septum and posterior fossa, and notes any window limitation. The combined pattern warrants further imaging review; absence from one image alone would not justify the same conclusion.
Watch the distinction: A structure that is unseen in one plane is not necessarily absent. Obliquity and a restricted window can mimic a malformation, so confirm landmarks and describe uncertainty.
31. Describe diffuse and extra-axial disease
Diffuse echogenic change is a pattern, not an etiology. Compare both hemispheres and deep gray structures, document symmetry and interval change, and consider whether altered gain or a different probe could account for apparent brightness. Hypoxic-ischemic injury may have characteristic distributions in a clinical context, while infection and calcification can produce other focal or diffuse patterns; ultrasound alone may not establish the cause. Evaluate extra-axial spaces separately from brain parenchyma. A fluid layer with internal echoes is more complex than simple clear fluid, but its contents cannot be named confidently from echoes alone. Use orthogonal views to establish location and thickness, and assess for mass effect. Communicate new or progressive findings promptly, specifying what changed and which structures are involved so clinical interpretation can integrate the event history.
Worked example: After a documented clinical event, repeat images show new bilateral deep gray echogenicity. A separate extra-axial layer contains mobile internal echoes and mildly displaces the adjacent surface. The sonographer checks comparable gain and planes, records the parenchymal and fluid findings separately, and promptly communicates the interval change. Neither appearance alone proves a single cause.
Watch the distinction: Labeling every new bright region hypoxic injury substitutes a cause for an observation. Technical settings, distribution, history, and other processes must be considered before that conclusion.
32. Calculate cerebral resistive index
Resistive index describes the proportionate fall from peak systolic to end-diastolic velocity: RI = (PSV − EDV) ÷ PSV. Use velocities from the same vessel and cardiac cycle, with a clean spectral envelope and consistent sample location. Because numerator and denominator have the same units, the result is dimensionless. Incorrect vessel identification, excessive wall filtering, or a poor envelope can distort the end-diastolic value and therefore the index. Note relevant clinical conditions and compare serial results only when technique is similar. RI is a waveform descriptor, not a direct measure of cerebral pressure or a stand-alone diagnosis. The sonography principles and instrumentation guide is useful for reviewing the Doppler settings that affect the waveform before calculating from it.
Worked example: In a hypothetical cerebral arterial sample, peak systolic velocity is 0.80 m/s and end-diastolic velocity is 0.20 m/s. Subtract to get 0.60 m/s, then divide: 0.60 ÷ 0.80 = 0.75. Report RI as 0.75, identify the sampled vessel, and describe the acquisition conditions. The calculation does not supply a universal normal cutoff.
Watch the distinction: Dividing EDV by PSV gives 0.25 in this example, which is a different ratio. RI subtracts EDV from PSV first, then divides by PSV.
Infant spine and spinal canal
33. Check the spinal window
Spinal sonography depends on an acoustic path through incompletely ossified posterior elements. As ossification increases, bone shadow can obscure the conus, filum, and nerve roots. Start by checking whether the referral question can actually be answered in longitudinal and transverse views. Adjust probe position and frequency, examine available interlaminar spaces, and use recognizable landmarks, but do not infer a conus level from a partly hidden tip. A study may still describe visible superficial or upper canal findings while remaining limited for tethering assessment. Record the specific anatomy that could and could not be seen and the reason, such as persistent posterior shadowing. That distinction helps the clinical team choose further assessment without treating a technically incomplete study as reassuring.
Worked example: In an older infant referred for possible low conus, posterior shadowing hides the conus tip in both longitudinal and transverse attempts. The sonographer documents the best views and states that conus localization is not possible on this examination. A visible segment of cauda equina does not supply the missing termination level. The referral question therefore remains unresolved.
Watch the distinction: Assigning a normal conus level from its last visible segment confuses visibility with termination. If the tip is hidden by bone, the level remains indeterminate.
34. Number vertebral levels
A conus level is only as reliable as the vertebral count beneath it. Number from a clearly identified landmark and cross-check by another method, such as counting ribs and lumbar-type vertebrae, identifying the lumbosacral junction, or correlating with available imaging. Each method has pitfalls. A small rib may be missed, and a transitional vertebra may make an extra or fused segment look ordinary. Mark the count on a longitudinal image and state how the level was assigned. If methods disagree, revisit the anatomy before labeling the conus; unresolved discrepancy should remain explicit in the report. A precisely drawn caliper at an incorrectly numbered level is still a wrong localization. The aim is reproducibility for subsequent imaging and clinical comparison.
Worked example: A sacral-up count makes one body appear to be L5, but a rib-based count suggests an extra lumbar-type segment. The sonographer repeats both sweeps and reviews the lumbosacral junction. If the discrepancy persists, the report states both counting methods and the uncertainty; it does not label the conus as ending at L5 from the first count alone.
Watch the distinction: Counting upward from the sacrum without checking for transitional anatomy can shift every lumbar label. The conus then appears higher or lower because the numbering changed.
35. Identify normal canal anatomy
Identify canal structures by their relationships, not by one bright line. In longitudinal view, the cord tapers into the conus; below it, the thin filum courses among the cauda equina roots within anechoic cerebrospinal fluid. A small central canal may be visible within the cord. Rotate to transverse view to confirm that a suspected structure is central or peripheral and to distinguish individual moving roots from the filum. Gentle observation during spontaneous movement can show root motion, while excessive probe pressure or poor frame rate can make motion difficult to judge. Record the conus tip, filum appearance, surrounding fluid, and whether roots move freely. These landmarks establish the basis for later assessment of tethering or a mass; brightness by itself does not identify a structure.
Worked example: Below a clearly tapered conus, a thin central echogenic strand continues caudally. Separate roots move around it within visible cerebrospinal fluid, and transverse views confirm the strand's central position. These findings support identification of the filum and mobile cauda equina. The sonographer records the conus level separately because identifying the filum does not establish where the conus ends.
Watch the distinction: A single echogenic line below the cord is not enough to identify the filum. Confirm its continuity and position while separating it from mobile nerve roots.
36. Assess possible tethering
Possible tethering is assessed through several linked observations: where the conus ends, how the filum looks, and whether the cauda equina moves within the fluid space. First establish vertebral numbering, then document the conus tip in two planes. Examine filum thickness and echogenicity at the specified site; fat can make a filum unusually bright. Observe root motion without mistaking probe movement for intrinsic movement. Apply the reference criteria given for the case, while recognizing that an uncertain level or poorly seen filum weakens the conclusion. A low conus with an abnormal filum and restricted motion is a more coherent concerning pattern than an isolated borderline measurement. Describe each component and the technical limits so the interpreting clinician can integrate skin findings and other imaging.
Worked example: A hypothetical case defines concerning features as a conus below L2 and a filum thicker than 2.0 mm at the stated site. Reliable numbering places the conus at L3, the filum measures 2.4 mm, and roots show reduced motion. Both stated criteria are met, with supporting dynamic evidence. Report the combined concern for tethering and the measurement method.
Watch the distinction: Calling tethering from one uncertain conus level ignores numbering error and associated findings. Confirm the level, filum, and root motion before describing the pattern.
37. Examine open spinal defects
For a suspected dorsal spinal defect, map the skin, posterior bony elements, canal, and any external sac as continuous layers. Determine whether the skin covering is intact or interrupted and show the sac's neck in longitudinal and transverse views. Fluid alone within a communicating sac suggests a different anatomic pattern from a sac that also contains neural tissue. Identify cord or roots entering the sac when visible, and document the involved vertebral levels and adjacent canal abnormalities. Avoid pressing directly on a fragile exposed lesion. Sonography may not show the full extent if the window is restricted, so specify what remains uncertain. The sonographer's description of continuity and contents is more useful than a label based only on the sac's outward shape.
Worked example: A newborn has a dorsal sac at the lower spine. Two planes show an interruption in the posterior elements, communication with the spinal canal, and neural tissue extending into the sac. The sonographer documents the skin covering, defect level, sac contents, and adjacent cord. Because neural tissue is present, describing it as a fluid-only meningocele would be inaccurate.
Watch the distinction: A fluid-filled appearance on one image does not prove a sac contains only fluid. Trace its neck and look for neural tissue in orthogonal views.
38. Trace a cutaneous tract
A midline skin opening, unusual dimple, or other marker can signal a tract toward the spinal canal. Begin at the skin and follow any visible channel continuously in longitudinal and transverse planes, recording depth, direction, and whether it reaches the posterior elements or canal. Look for an associated collection, echogenic lipomatous tissue, or divided canal contents that could suggest additional abnormalities. A tract that disappears beneath acoustic shadow is not proven to stop there; report the point at which continuity becomes uncertain. Avoid compressing a tender or draining opening to force a view. Because a possible dermal sinus can provide a pathway toward deeper structures, a suspected canal connection is a finding to communicate promptly. Describe the observed course rather than asserting a complete path from one short image.
Worked example: A newborn has a small midline opening above the gluteal region. Ultrasound shows a narrow hypoechoic tract descending from the skin toward a posterior element gap. It is visible in two planes but its deepest segment is obscured. Document the demonstrated course and the obscured segment, then communicate possible canal continuity for specialist review.
Watch the distinction: Losing sight of a tract under bone shadow does not show that it ends safely. The report should distinguish its visible course from the unresolved deep connection.
39. Separate spinal variants from lesions
Some small fluid spaces in the infant spinal canal are developmental appearances. A filar cyst is typically a small, simple fluid focus associated with the filum; a prominent central canal follows the cord's center. Confirm location and continuity in two planes before naming either. Assess size, internal echoes, mass effect, surrounding fluid, and root motion. A tiny uncomplicated space with freely moving roots has a different pattern from an enlarging, complex collection that displaces or restricts neural structures. Compare serial images at the same level when change is claimed. Hemorrhage and infection may also create complex material, so clinical context and evolution matter. The sonographer should describe concerning complexity or mass effect and communicate it, while avoiding a definitive cause based solely on fluid appearance.
Worked example: A tiny anechoic focus lies along the filum, has a thin smooth boundary, and causes no root displacement; roots move freely. Those observations favor a small filar cyst. If follow-up instead shows a larger complex collection with new root restriction, record the interval change and communicate concern for a pathologic process.
Watch the distinction: Treating every canal cyst as dangerous ignores position and mass effect. Treating every fluid space as a harmless variant ignores growth, internal complexity, and restricted roots.
Pediatric musculoskeletal sonography
40. Validate the infant hip plane
Infant hip angles depend on a valid image plane. In the standard coronal assessment, seek a straight iliac wing, the acetabular bony roof and edge, the femoral head, and the labral or cartilaginous structures required by the stated method. An oblique plane can make the roof appear shallow and alter the angle even when calipers are placed neatly. Obtain reproducible coronal images and transverse views that establish femoral head position and coverage. Confirm that the child and probe are positioned as required before measuring. Dynamic assessment, when indicated, uses the approved technique and trained personnel; a static angle cannot describe stability. If the required landmarks are missing, label the image technically unsuitable and reacquire it. Interpretation of morphology should follow valid acquisition and the age-specific criteria supplied for the case.
Worked example: An initial coronal image appears to show a shallow acetabulum, but the iliac line curves because the probe is oblique. The sonographer repositions until the iliac line is straight and the bony roof, edge, femoral head, and required cartilage landmarks are visible. Only the corrected image is used for an angle; the first appearance cannot establish dysplasia.
Watch the distinction: A precise angle drawn on an invalid plane remains invalid. Missing bony landmarks or a curved iliac line should trigger reacquisition before acetabular morphology is interpreted.
41. Interpret hip coverage
Infant hip morphology must be judged from a valid standard plane: the iliac line, acetabular roof and labrum need to be recognizable before an angle or coverage estimate means much. The bony roof angle describes acetabular development, while femoral head coverage describes how much of the head remains seated within the socket. These measures answer related but different questions. A shallow roof can reduce coverage, yet probe rotation can also make a normal roof appear shallow. Check the head position, roof contour and measurement landmarks together, then apply the age-specific classification supplied with the case. Cartilage and ossification change with maturation, so age matters when interpreting the same appearance. The ARDMS identifies Pediatric Sonography among its exams; in practice, the sonographer records reproducible images and measurements for clinical interpretation.
Worked example: A hypothetical case specifies that the relevant angle should be at least 60 degrees for this infant's age. The required landmarks are visible on a repeat coronal image, so the measured 54 degrees is 6 degrees below that case criterion. The bony roof also appears shallow, and the femoral head has reduced coverage. Together these findings support abnormal morphology under the supplied rule; the angle alone would be less persuasive.
Watch the distinction: A low angle on an oblique image is not evidence of dysplasia. Reacquire the required plane and check coverage and roof shape before applying an age-specific criterion.
42. Assess hip stability safely
A dynamic hip study asks whether the femoral head stays centered as position or gentle stress changes. First document the resting relationship between the head and acetabular rim in reproducible views. During a maneuver permitted by the examination protocol and performed by trained personnel, watch the head relative to a fixed bony landmark. Positional change alters the view without true translation of the head; laxity allows motion while containment persists. Subluxation means partial loss of contact or coverage, whereas dislocation means the head leaves the socket. Note whether displacement occurs only with stress, whether it reduces afterward and whether the finding repeats. Forceful manipulation can cause harm and can distort the assessment. Record what moved and under which conditions, leaving classification and management decisions to the responsible clinician.
Worked example: At rest, an infant's femoral head is centered. During an authorized gentle maneuver, the same bony reference remains fixed while part of the head moves beyond the acetabular rim. When stress stops, the head returns to its resting position. The reproducible partial displacement supports dynamic subluxation. It is not a fixed dislocation because the head is seated at rest and reduces when stress ends.
Watch the distinction: A changing hip image does not automatically demonstrate instability. If the iliac landmark moves with the head, probe motion or a different imaging plane may explain the apparent displacement.
43. Characterize a joint effusion
Joint fluid separates the capsule from adjacent bone and may collect in a recess that is easy to compare with the opposite side. Scan both hips in comparable positions and planes, measuring from consistent landmarks when a measurement is requested. Look for simple anechoic fluid, internal echoes, synovial thickening and increased flow in adjacent tissue. These describe the joint environment but do not identify the cause: infection, inflammation, trauma and other processes can overlap. A small amount of fluid may also be physiologic or difficult to distinguish from asymmetry caused by probe pressure. If symptoms or imaging findings raise concern for a septic joint, communicate promptly because clinical assessment and, when indicated, fluid analysis guide that determination. The sonographer should describe the effusion and associated findings, not label the fluid septic from appearance alone.
Worked example: A febrile child with a painful right hip has a visibly expanded right anterior recess compared with the left in matched views. The right synovium is thickened and shows increased adjacent Doppler signal. Report an asymmetric effusion with synovial change and communicate the concern promptly. These observations support active joint disease, but they cannot distinguish septic fluid from another inflammatory effusion on their own.
Watch the distinction: Echoes or synovial thickening do not prove bacterial infection. Clinical findings, laboratory results and sometimes aspiration are needed; a quiet-looking effusion also cannot exclude serious disease.
44. Inspect bone surfaces
A high-frequency probe shows the bright outer cortical surface of accessible bone, but sound does not penetrate intact cortex to evaluate marrow directly. Sweep along and across the tender area to look for cortical interruption, periosteal lifting and fluid or soft tissue change beside the bone. A subperiosteal collection may occur with infection or trauma; its shape and surrounding hyperemia add context but do not establish a single cause. Compare an adjacent unaffected segment and, where useful, the other side. In children, an open growth plate and developing ossification center can resemble a break unless their expected location and smooth margins are recognized. Ultrasound samples only the visible surface, so an intact scanned segment does not clear the entire bone of fracture or marrow disease. Document the precise site and extent of the visible abnormality.
Worked example: A child has focal tibial tenderness. Longitudinal and transverse scans show fluid lifting the periosteum over one segment, with adjacent soft tissue swelling, but no definite cortical interruption in the accessible surface. The sonographer documents the collection's length and location and communicates the finding. An unseen fracture or marrow infection remains possible despite the absence of a visible cortical break.
Watch the distinction: A smooth cortex under a tender area is not a complete negative bone study. Ultrasound cannot assess hidden cortex or marrow well, and pediatric growth structures need careful recognition.
45. Examine soft tissue injury
Tendons reflect sound most strongly when the beam meets their fibers nearly at a right angle. If the beam is oblique, a normal fiber bundle may look dark, a phenomenon called anisotropy. Before calling a tear, tilt or rock the transducer and see whether the normal fibrillar pattern returns. Then examine the suspected gap in both long and short axes. A real tear tends to persist across appropriate angles and may show discontinuous fibers, retraction or fluid in the defect. For a muscle injury, document the location within the muscle or at its junction with tendon, the extent of disrupted fibers and any collection. A hematoma may have mixed echoes as blood evolves and may deform with gentle compression. Use dynamic movement only when appropriate for the child's pain and injury.
Worked example: A dark band in a child's tendon becomes uniformly bright and fibrillar when the probe is tilted perpendicular to its fibers. No persistent gap appears on the transverse view, supporting anisotropy. Beside it, a complex intramuscular pocket remains visible in both planes and changes shape under light compression. That persistent collection supports a muscle hematoma, while the tendon finding does not establish a tear.
Watch the distinction: A single dark tendon frame is not sufficient evidence of rupture. Correct the beam angle and verify fiber disruption in an orthogonal plane before interpreting it as a tear.
46. Map an extremity mass
Begin a palpable extremity mass study by placing the finding in a compartment: skin, subcutaneous tissue, muscle, joint or near bone. Scan in two planes and document three dimensions, internal architecture, compressibility, Doppler flow and the relationship to nearby vessels and nerves. Fluid may deform and show posterior enhancement; a vascular channel may collapse with light pressure and refill. Solid tissue generally maintains its structure, although some lesions mix solid and cystic parts. Compare the finding with expected pediatric anatomy. Cartilage is less echogenic than ossified bone, a growth plate forms a normal gap, and an ossification center may have an irregular developmental contour. Follow these structures in adjacent views before calling a fragment or mass. A confident description of origin and relationships is more useful than assigning a specific lesion type from one feature.
Worked example: A calf lump lies within subcutaneous tissue beside an expected cartilaginous ossification center. It consists of several compressible channels, and optimized spectral Doppler shows slow venous flow. The center continues with normal adjacent anatomy, so it should not be called a loose fragment. Document the lesion's size, compartment and distance from the nearby neurovascular bundle; the findings support a venous-pattern lesion.
Watch the distinction: Low echo intensity near a growth plate is not automatically a cyst or fracture. Confirm developmental anatomy and use compressibility and optimized Doppler before classifying a nearby mass.
Thorax and diaphragm
47. Describe pleural fluid
Pleural fluid appears between the chest wall and lung and offers an acoustic window into adjacent compressed lung. Sweep through accessible spaces with the child positioned as tolerated, describing the fluid's distribution and qualitative extent. Simple fluid is usually uniformly dark; internal echoes, mobile debris or septa make it complex. These details help identify loculations and guide clinical planning, but hemorrhage, inflammation and infection can have overlapping appearances. Observe whether lung tissue moves within the fluid and whether its compression limits aeration. A small dependent pocket can be missed if only one position is scanned, while apparent echoes may arise from gain or motion. Record the accessible margins and any limitations. The American Institute of Ultrasound in Medicine provides general ultrasound practice resources, while the clinical team determines the effusion's cause.
Worked example: A child has fluid along the posterior pleura. As the child breathes, echoes move within the fluid, several thin septa remain fixed, and adjacent lung appears compressed. These observations justify reporting a complex pleural effusion with associated lung compression. They do not establish empyema: blood or another inflammatory fluid may also be complex, and clinical findings or fluid analysis may be needed to distinguish them.
Watch the distinction: Complex pleural fluid is not synonymous with infection. Report echoes and septations as observations; cause depends on clinical context and sometimes fluid testing.
48. Assess accessible lung
Air strongly reflects ultrasound at the pleural surface, so ordinarily aerated lung hides structures deeper than that surface. When a peripheral region loses aeration, it can become tissue-like and accessible to sonography. Look for its shape, contact with the pleura, internal branching bright lines from air-filled bronchi and any adjacent fluid or irregular pleural line. Motion of air bronchograms with breathing can add information, but no single appearance establishes a cause. Atelectasis and inflammatory consolidation may overlap, especially in a child with pleural fluid. Sweep neighboring spaces to identify the accessible extent, then state which margins disappear behind air or bone. A normal pleural survey elsewhere samples only visible surfaces; it does not rule out deeper disease concealed by aerated lung or ribs.
Worked example: At the right posterior chest, a wedge of tissue-like lung reaches the pleural surface and contains branching bright structures that move slightly with breathing. This supports a peripheral consolidation with air bronchograms. Other scanned surfaces show normal pleural lines, but that does not clear the deeper right lung because its air-filled regions block the beam. Report the location, visible extent and any adjacent effusion.
Watch the distinction: A normal accessible lung surface is not a complete normal lung examination. Aerated tissue and ribs conceal deeper lesions, and tissue-like lung must be interpreted with clinical context.
49. Evaluate possible pneumothorax
At a lung surface, pleural sliding reflects relative motion of visceral and parietal pleura during breathing. B-lines arise at that surface and move with sliding; their presence at a scanned point argues that the pleural layers meet there. Pneumothorax separates the layers with air, often removing sliding and B-lines in that region. The strongest described sonographic clue is a reproducible lung point, where a sliding region meets an adjacent region without sliding as the lung edge moves through the field. Absent sliding alone is nonspecific: shallow breathing, apnea, pleural adhesion and technical choices can also reduce visible motion. Stabilize the probe, compare regions and correlate with respiratory support and symptoms. If the pattern raises urgent concern, communicate it promptly while documenting where each sign was seen.
Worked example: A breathless child has no visible sliding or B-lines over one anterior region. On a neighboring interspace, repeated breaths reveal a stable boundary: sliding appears on one side and is absent on the other as the boundary moves. This reproducible lung-point pattern supports pneumothorax more strongly than absent sliding alone. The sonographer records both regions and promptly communicates the concerning finding for clinical action.
Watch the distinction: Absent sliding by itself does not prove pneumothorax. Confirm adequate respiratory motion and technique, search for a lung point where feasible, and weigh the child's clinical state.
50. Measure diaphragm motion
Diaphragm assessment requires a fixed view and comparable breathing conditions. In B-mode, identify the hemidiaphragm as a moving bright curved line and watch its direction during inspiration and expiration. M-mode places a sampling line through that motion over time, making excursion and direction easier to compare. Scan each side with similar positioning and document whether breathing is spontaneous, assisted or altered by distress. A reduced trace may reflect weak movement, limited effort or an unfavorable angle; apparent paradoxical movement may result from probe movement or transmitted motion from nearby structures. Stabilize the probe against a consistent landmark and repeat several breaths before describing asymmetry. If a numeric excursion is reported, use the same landmarks and respiratory phase on both sides. The SPI study guide can reinforce motion-display principles.
Worked example: During comparable spontaneous breaths, the right hemidiaphragm moves in the expected inspiratory direction while the left appears to move oppositely on M-mode. The sonographer braces the probe, confirms the diaphragm in B-mode and repeats several cycles. The reversed left-sided movement persists, supporting a description of paradoxical motion. Record breathing conditions and technique, since an unsteady probe or ventilator cycle could otherwise create a misleading trace.
Watch the distinction: One unusual M-mode slope is not proof of paralysis. Probe motion, oblique sampling and unequal breaths can reverse or shrink the apparent trace; repeat under documented conditions.
51. Recognize the thymus
The thymus is prominent in many children and can occupy a substantial part of the anterior mediastinum. Its sonographic texture often contains fine, evenly distributed bright lines or speckles within softer tissue. Sweep across the finding to test continuity and look for a smooth shape that conforms to neighboring structures. Unlike an aggressive focal mass, normal thymic tissue generally does not create a discrete invasive margin or markedly displace adjacent vessels. A focal thymic lesion or another mediastinal structure can still complicate the appearance, so symmetry and texture are supporting clues rather than a final diagnosis. Use accessible suprasternal or parasternal windows, identify vessel relationships and describe what is obscured by bone or air. Document a focal area separately if it interrupts the otherwise continuous thymic pattern.
Worked example: A child referred for an apparent anterior chest mass has a soft structure extending across adjacent suprasternal views. It has uniform fine internal echoes, blends with similarly textured tissue on each side and does not displace the nearby vessels. This combination favors normal thymic tissue. The sonographer records the continuous morphology and vessel relationships, while acknowledging that the deepest portion is limited by the sternum.
Watch the distinction: A prominent thymus is not automatically a tumor. Follow its continuity and typical texture, but investigate a separate focal abnormality rather than assuming every anterior mediastinal finding is normal thymus.
52. Inspect diaphragm anatomy
The diaphragm separates thoracic from abdominal contents. To assess a suspected defect, follow its bright contour across available windows and look for interruption, abdominal organs above the expected line and their motion with breathing. Demonstrating bowel loops or liver tissue in the chest adds anatomic support to a hernia pattern. Eventration instead raises an intact portion of diaphragm, often with altered excursion, without a full-thickness opening. Respiratory motion can blur the contour, and aerated lung or ribs may hide part of a defect, so two planes and organ continuity are valuable. Identify the liver, spleen and bowel correctly before describing displacement; the RDMS abdomen study guide provides related abdominal anatomy review. Report the observed anatomy and imaging limits for further clinical characterization.
Worked example: In a child with an elevated left hemidiaphragm, repeated scans show bowel loops containing gas and fluid above a visible break in the diaphragmatic contour. The loops connect to abdominal bowel through the defect. This supports a diaphragmatic hernia pattern. If the contour had remained intact and elevated throughout the sweep, with reduced excursion but no organs passing through it, eventration would be the stronger description.
Watch the distinction: An elevated diaphragm alone does not demonstrate a hernia. Look for a true contour defect and displaced abdominal contents; an intact elevated sheet favors eventration or another cause.
53. Describe congenital thoracic lesions
A congenital lesion near the lung may be seen when it reaches the pleural surface or creates a fluid-filled acoustic window. Describe whether the accessible portion is cystic, solid or mixed; note cyst size variation, internal debris, septa and the relationship to adjacent lung. Color and spectral Doppler may reveal a feeding vessel or drainage route, but absence of a visible vessel is limited by depth, motion and slow flow. Trace the lesion in orthogonal planes and record whether its deep boundary vanishes behind aerated lung. These findings can suggest a developmental thoracic abnormality, yet sonography may not define its entire extent or vascular anatomy. Keep the report anchored to what was actually seen and communicate any compression, effusion or respiratory concern. Further imaging may be needed to map hidden structures.
Worked example: An infant has a peripheral multicystic region visible between ribs. Its superficial margin and several unequal cysts are clear in two planes, but the deep edge disappears behind aerated lung. Doppler shows no definite feeder in the accessible portion. Report a partially visualized multicystic thoracic lesion and the vascular assessment limit. The missing deep margin and unseen feeder cannot be treated as proof of limited size or absent supply.
Watch the distinction: A clear superficial view does not show the entire thoracic lesion. Air can hide the deep boundary, and Doppler can miss small or slow vessels.
Superficial structures, neck and vascular abnormalities
54. Assess pediatric thyroid findings
Pediatric thyroid evaluation starts with gland location, lobe dimensions, overall echotexture and any focal lesion. For a nodule, document composition, echogenicity, margins, shape and echogenic foci in orthogonal views. Survey adjacent cervical nodes for shape, preserved or lost fatty hilum, internal echoes, calcification-like foci and vascular pattern. A suspicious node can materially change the clinical picture even when the thyroid lesion is small. Pediatric thyroid disease differs from adult disease in prevalence and management, so adult size-based decision rules should not be transferred automatically. Do not assign cancer from a sonographic feature alone: irregular margins and punctate bright foci increase concern but have mimics, including artifact. Describe the finding and its nodal relationship precisely, then ensure concerning observations reach the interpreting and clinical team through the established pathway.
Worked example: A child's thyroid nodule has irregular edges and multiple punctate bright foci on two planes. A nearby node is rounded, lacks a visible fatty hilum and contains similar foci. Record the nodule's dimensions and features, map the node by side and level, and communicate the combination for pediatric review. The pattern is concerning, but ultrasound alone does not establish malignancy or dictate an adult management pathway.
Watch the distinction: A thyroid nodule's size alone should not drive a pediatric conclusion. Morphology and adjacent nodes matter, and adult management algorithms cannot simply be imposed on a child.
55. Examine nodes and salivary glands
A neck complaint may arise from a lymph node, salivary gland, duct or surrounding soft tissue. A typical reactive node is often oval with a central echogenic hilum and predominantly hilar flow, though appearances overlap. Assess size in two planes, cortical thickness, margin, internal breakdown and vascular distribution, then look for edema or a collection around it. Examine adjacent salivary glands for enlargement, altered echotexture and ductal dilatation. A bright focus in a dilated duct, especially with shadowing, can redirect the localization toward a ductal deposit. Probe pressure and Doppler settings affect apparent flow, so compare similar settings across nearby structures. Describe both the node and gland rather than deciding from tenderness alone. An abnormal node can coexist with gland disease as a regional response.
Worked example: A child has a tender upper-neck lump. The palpable node is enlarged but oval, retains a central hilum and shows mainly hilar flow. The adjacent salivary gland is swollen, and its duct is dilated around a bright shadowing focus. The ductal finding localizes a likely source of the complaint to the gland; report the node as an associated finding rather than assuming it is the primary lesion.
Watch the distinction: The most tender palpable structure is not necessarily the source. Survey adjacent ducts and glands, and do not infer benignity from a preserved nodal hilum alone.
56. Locate congenital neck lesions
Congenital neck lesions are best approached through location and continuity. A midline lesion near the hyoid suggests a thyroglossal duct pathway; a lateral lesion along a characteristic cervical course may suggest a branchial cleft abnormality. Multiloculated, infiltrative fluid spaces crossing tissue planes raise a lymphatic pattern. These patterns overlap when lesions become infected or bleed, so describe walls, internal echoes, solid components and surrounding inflammation as well. Follow the lesion in two planes toward the tongue base, thyroid bed or deeper neck as visibility permits. A midline mass can occasionally represent ectopic thyroid tissue, making it useful to document whether thyroid tissue is visible in its expected position. Sonography establishes relationships and composition; it does not prove an embryologic origin from location alone.
Worked example: A child has a midline cystic lump closely related to the hyoid. Its position and course support a thyroglossal duct lesion. The sonographer also surveys the expected thyroid bed and documents normally located thyroid tissue there. If the thyroid bed appeared empty or the lesion contained thyroid-like solid tissue, ectopic thyroid would need consideration before the finding was treated as an ordinary cyst.
Watch the distinction: A midline cyst near the hyoid is suggestive, not definitive, for a thyroglossal duct lesion. Check the thyroid bed and describe any solid tissue or atypical course.
57. Classify vascular flow patterns
Vascular abnormalities should be classified first by observed flow behavior, not by color brightness alone. Map channel size and distribution in gray scale, test gentle compressibility and refill, then optimize Doppler for expected velocity. Slow venous channels may show little color until the scale and wall filter are reduced; spectral tracing then typically has low-velocity, nonpulsatile flow. Arterialized channels show pulsatile flow and may connect to a feeding artery or high-flow shunt. Some vascular tumors have solid tissue with internal vascularity rather than discrete compressible channels. Motion and excessive color gain can create false signals, while pressure can collapse real slow-flow channels. Document the settings and waveform where useful, plus lesion depth and nearby structures. The sonographer can describe a flow pattern without assigning a final vascular anomaly subtype from limited images.
Worked example: A child's forearm lesion contains several compressible tubular spaces. At the initial high color scale, none fills with color; after lowering the scale and wall filter, slow flow appears, and a sampled channel has a nonpulsatile low-velocity waveform. The combined morphology and optimized flow support a venous-pattern lesion. The original empty color box reflected insufficient sensitivity, not proof that the channels were avascular.
Watch the distinction: No color signal does not mean no blood flow. Recheck scale, wall filter, gain, pressure and motion before deciding whether a suspected vascular channel is truly unperfused.
58. Characterize superficial collections
A superficial inflammatory area can show diffuse edema, a defined fluid pocket or a solid-appearing focus. Survey in two planes to establish whether a pocket has a measurable boundary, internal debris or mobile echoes, and posterior enhancement. Doppler often shows flow in inflamed surrounding tissue while a fluid center lacks internal flow; a solid mass may contain internal vascularity. Too much probe pressure can collapse a small collection, so use a generous gel layer and gentle contact. Record three dimensions, depth from skin, relation to fascia and proximity to vessels or nerves. A collection's appearance may make it technically accessible for drainage, but imaging does not authorize intervention or establish the organism. Communicate rapidly spreading inflammation or other urgent clinical concern while keeping the report descriptive.
Worked example: At a tender forearm site, ultrasound shows a defined complex subcutaneous fluid pocket in both planes. Its center has no detectable internal flow after optimization, while its rim is hyperemic. The pocket lies superficial to fascia and near a small vessel. Report its dimensions, depth and vessel relationship as a drainable-appearing collection. Diffuse swelling alone would not provide the same evidence of a discrete fluid target.
Watch the distinction: Peripheral hyperemia does not make a collection a solid mass, and an avascular center does not authorize drainage. Document the pocket and adjacent anatomy for clinical decision-making.
59. Localize a foreign body
A foreign body may appear as a bright linear or punctate focus with posterior shadowing, reverberation or a surrounding hypoechoic inflammatory rim. Use a high-frequency probe and ample gel to visualize the shallow tissues without compressing the object away from its natural position. First find the suspected object in one plane, then rotate the probe to verify it in the orthogonal plane and determine its true length and orientation. Measure skin-to-object depth from the closest surface and record distance to a nearby vessel, nerve or tendon, including the direction of that structure. Doppler can help locate vessels before any clinical procedure is planned. Material and angle influence artifact, so the object may be conspicuous in one view and subtle in another. A single bright focus can also be scar or calcification.
Worked example: A child has a persistent puncture-site lump. A 7 mm linear bright object casts shadowing in long axis and appears as a short bright focus in transverse view. Its nearest edge lies 4 mm beneath the skin and 3 mm from a Doppler-confirmed vessel. Record its length, orientation and both distances for clinical planning; the two-plane match supports a real object rather than an isolated image artifact.
Watch the distinction: One bright dot is not enough to confirm a foreign body or its size. Verify it in two planes and measure its closest relationship to skin and vulnerable structures.
60. Calculate volume flow
Volume flow is cross-sectional area multiplied by cross-sectional mean velocity, so the diameter and Doppler velocity must refer to the same vessel segment. For a circular lumen, area equals π(d/2)². Diameter error matters greatly because area depends on its square: a small overestimate produces a larger flow overestimate. Use an inner-wall diameter measured perpendicular to the vessel, and use a velocity measure that represents the cross-sectional mean rather than substituting peak systolic velocity. Consistent units are essential: square centimeters times centimeters per second gives cubic centimeters per second, equivalent to milliliters per second. Pulsatility, an elliptical lumen, disturbed flow or imperfect angle correction weaken the estimate. Report the assumptions and measurement site with the calculated value. For further calculation practice, see the PS practice questions.
Worked example: Suppose a hypothetical vessel has a circular inner diameter of 0.20 cm and representative mean velocity of 20 cm/s. Radius is 0.10 cm, so area is π × (0.10 cm)² = 0.0314 cm². Flow is 0.0314 cm² × 20 cm/s = 0.628 cm³/s = 0.628 mL/s. Multiplying by 60 gives about 37.7 mL/min. This estimate assumes circular shape and representative mean velocity.
Watch the distinction: Peak systolic velocity cannot be inserted as mean velocity without overestimating volume flow. Measure diameter consistently, square the radius, preserve units and state the circular-lumen assumption.