EUS Section Pediatric EM Subcommittee
Lorraine K. Ng, MD Associate Professor, Asst Director of Emergency Ultrasound, Columbia University Irving Medical Center, New York
Maytal Firnberg, MD Pediatric Emergency Medicine Fellow, Columbia University Irving Medical Center, New York
Intussusception is the most common cause of intestinal obstruction in children less than 2 years of age. While it should be considered in older children as well, 80-90% of cases occur in children younger than 2 years.1 It occurs when a segment of bowel telescopes into another segment of bowel, and most often occurs at the ileocecal junction. As intussusception develops, the mesentery is dragged into the bowel which leads to venous and lymphatic congestion and ultimately leads to ischemia, perforation, and peritonitis if untreated. While lead points such as lymphoid hyperplasia, polyps, and tumors are sometimes identified, these account for only about 25% of cases. The majority of cases in children are idiopathic.2
The presentation of intussusception can be variable and age dependent. Abdominal pain is the most common presenting symptom but can be difficult to interpret in younger non-verbal children. Vomiting is also common across age groups. Classically, intermittent episodes of screaming and abdominal pain are described with a drawing up of the knees towards the chest. Mental status changes have also been described as alternating periods of lethargy and irritability. Bilious vomiting and lower gastrointestinal bleeding are late findings with the classic ‘currant jelly’ stools occurring in less than 50% of cases. Occasionally, a sausage-shaped mass may be palpated in the right upper quadrant, but this is appreciated in less than a third of patients.1
While X-rays may be helpful to evaluate for the presence of intussusception, ultrasound is the diagnostic modality of choice. In experienced hands, ultrasonography has excellent test characteristics with both sensitivity and specificity of >97% and a negative predictive value of 99.7%.3 At the bedside, pediatric emergency physicians with limited and focused training are also able to accurately diagnose ileocolic intussusception with a sensitivity of 85% and a specificity of 97%.4
Classically, intussusception manifests in the transverse orientation as a ‘target sign’ or ‘donut sign’ (Figure 1) representing layers of intestine within the intestine. In the longitudinal orientation, the layers of intestine appear as a ‘pitchfork’ or ‘submarine sandwich’ (Figure 2). These findings are most commonly seen in the right lower quadrant for ileocolic intussusception, which is the most common type of intussusception. Small bowel intussusceptions can be differentiated by their size, which are often ≤3 cm.5 While small bowel intussusceptions often spontaneously reduce, if symptoms and findings persist, computed tomography (CT) may be necessary to determine management. POCUS is useful in differentiating variants of intussusception that range from a surgical emergency to a transient source of abdominal pain allowing clinicians to better manage these patients.6
Some processes that cause bowel wall thickening such as infectious or inflammatory colitis can be misinterpreted for multiple layers of bowel wall seen in intussusception. Intermittent intussusception can be missed if it self-reduces before the scan. An operator that does not adequately adjust their depth or systematically scan the abdomen may miss an intussusception.