Episodic abdominal pain is caused by the process of one segment of the bowel telescoping into another segment during intestinal peristalsis. While telescoping is most often idiopathic in nature, a Meckel diverticulum, viral infections, and the rotavirus vaccine can all cause lead points for telescoping. It is painful because this telescoping results in ischemia.
Patients are irritable and have diarrhea with intussusception, especially if associated with other intestinal pathologies.
On physical exam, these children can have a “sausage-shaped” mass, which is typically found in the right upper quadrant (RUQ). Furthermore, there is no fullness in the bowel, and there is an empty right lower quadrant (RLQ), otherwise known as “Dance’s sign.” On ultrasound, which is a reliable screening tool in low-risk patients, this mass may be seen as concentric echogenic bands formed by mucosa and muscularis alternating with hypoechoic bands formed by submucosa, otherwise described as “target sign," "doughnut sign," or "bull’s eye sign.”
With the telescoping that occurs in intussusception, arterial blood flow stops, leading to ischemia and pouring of mucus into the intestine. Venous engorgement also occurs, and together these processes form a mix of blood, mucus, and stool typically described as “red currant jelly stools.”
A conservative management technique involves air or hydrostatic enema. An air enema is performed by instilling air into the colon via catheter until it becomes so full that the telescoped bowel is pushed back into a normal position. A hydrostatic enema can be performed by instilling a crystalloid solution into the bowel and has a similar effect. Barium enemas are typically avoided as they can cause peritonitis if bowel perforation occurs.
If other conservative treatments are unsuccessful, the child may require surgical intervention. Here, the invagination (telescoping) is manually reduced, and nonviable intestine is resected. This is typically done laparoscopically.
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