The ultrasound image shows a classic "target sign" or "donut sign," characterized by concentric rings of alternating echogenicity. This sonographic finding is pathognomonic for intussusception, particularly when seen in the transverse plane.
Intussusception occurs when a segment of bowel telescopes into an adjacent segment, typically in children aged 6 months to 3 years. It commonly presents with intermittent abdominal pain, vomiting, and sometimes
"red currant jelly" stools.
Key ultrasound features of intussusception:
* Target sign in transverse view (concentric rings of bowel layers)
* Pseudokidney or sandwich sign in longitudinal view
* May show intraluminal mesenteric fat or vessels dragged in with the intussusceptum Comparison of answer choices:
* A. Bowel obstruction may show dilated loops of bowel with air-fluid levels and to-and-fro peristalsis but lacks the concentric ring sign.
* B. Diverticulitis typically shows bowel wall thickening and pericolic fat stranding; not the concentric target appearance.
* C. Appendicitis may appear as a blind-ending tubular structure (>6 mm), not with concentric ring pattern.
* D. Intussusception - Correct. The image demonstrates the classic target sign seen with this condition.
References:
Coley BD. US of gastrointestinal tract abnormalities in infants and children. Radiographics. 2005;25(1):27-47.
Rumack CM, Wilson SR, Charboneau JW, Levine D. Diagnostic Ultrasound, 5th ed. Elsevier; 2017.
AIUM Practice Parameter for the Performance of Pediatric Ultrasound (2021).