Intussusception occurs when a proximal segment of the bowel telescopes into an adjacent distal segment. It is one of the most common abdominal emergencies in children but is rare in adults. Intussusception commonly occurs near the ileocecal junction, where the intussusceptum telescopes into the intussuscipiens, dragging the associated mesentery with it. This leads to the development of venous and lymphatic congestion with resulting intestinal edema, which can ultimately lead to ischemia, perforation, and peritonitis. Rarely, the proximal bowel is drawn into the lumen of the distal bowel (retrograde intussusception); this phenomenon is seen in Roux-en-Y gastric bypass surgery. The majority of cases in children are idiopathic, although evidence points to a preceding viral infection triggering the intussusception in some of these cases. On the other hand, adults usually have a distinct underlying pathologic lead point, which can be malignant in half of cases. Intermittent abdominal pain is the most common presentation in both children and adults. Symptoms progress over time and are accompanied by nausea and vomiting. In children, a sausage- shaped abdominal mass may be felt in the right side of the abdomen accompanied by the “currant jelly” stool mixed with blood and mucous.
An intussusception is sometimes discovered incidentally during an imaging study performed for other reasons or for nonspecific symptoms. If these intussusceptions are short and if the patient has few symptoms, intervention may not be required.
Ultrasonography is the method of choice for detecting intussusception in children and can demonstrate layers within the intestine (target sign). Plain abdominal x-rays are less sensitive and are used to exclude other causes and confirm the presence of small bowel obstruction. In adults, CT scanning is the investigation of choice, on which the target sign is also seen.
The treatment approach differs in pediatric and adult populations. In stable children with no signs of bowel perforation, nonoperative reduction using either hydro- static or pneumatic enema is preferred to surgery. With this approach, the recurrence rate reaches 10%. In adults, surgical resection of the involved segment is recommended. Pathologic evaluation is needed to rule out underlying malignant disease.