Intussusception is the invagination of one segment of bowel into a distal bowel segment. The most common area of intussusception is ileocolic, but intussusception can be ileoileal, colocolic or ileoileocolic.
The peak age of intussusception is 6 to 12 months (generally 3 to 30 months but can occur at any age).
Intussusception is approximately twice as common in boys as it is in girls.
Lymphoid hyperplasia of the Peyer patches is thought to be the lead point of intussusception in most cases.
Adenovirus infection can cause lymphoid hyperplasia and predispose to intussusception.
In one third of cases of intussusception in children older than 2 years, a pathologic lead point is found. The most common pathologic lead point identified is a Meckel diverticulum. Other potential lead points include Henoch-Schönlein purpura, polyps, lymphomas, hemangiomas, intestinal duplications, and gastrojejunostomy tubes.
The classic triad of symptoms of intussusception is intermittent severe abdominal pain, vomiting, and grossly bloody or "currant jelly" stool. Unfortunately, this triad is present in only 20% of cases. Gross blood and currant jelly stool are late findings (Figure 2). Hemoccult-positive stool is common in intussusceptions, so stool should be tested for the presence of occult blood.
There are multiple cases in the literature of intussusception presenting with a chief symptom of lethargy. One proposed mechanism for the lethargy is a release of endogenous opioids in response to the pain of intussusception.
Figure 2. Photo courtesy of Michael Diament, MD.
Management – Diagnosis
A sausage-shaped mass might be palpated in the right upper quadrant.
Abdominal radiographs can suggest the diagnosis. There are two pathognomonic findings of intussusceptions: the crescent or meniscus sign, which is the rounded edge of the intussusceptum entering into the gas-filled distal bowel segment, and the target sign, which represents alternating layers of fat and mucosa (Figure 3). Other suggestive findings are absence of gas and stool in the cecum, paucity of bowel gas, a soft tissue mass, or a small bowel obstruction. A normal abdominal radiograph does not rule out intussusception.
The sensitivity of ultrasonography for the diagnosis of intussusception approaches 100%. An intussusception appears as an approximately 5-cm soft tissue mass; it can look like a target, with a hypoechoic rim surrounding an echogenic center. Other benefits of ultrasonography are lack of radiation exposure and identification of pathologic lead points.
Some centers use ultrasonography-guided air or saline enema reduction for treatment of intussusception.
Air or barium enema under fluoroscopy is diagnostic and potentially therapeutic. The success rate of nonsurgical reduction of intussusception varies with the experience of the radiologist. In experienced hands, successful reduction with fluoroscopy-guided barium enema is reported in 70% to 85% of cases. The success rate of air enema is reported to be higher than 90%. Multiple attempts at reduction might be required. The risk of perforation with barium or air enema is very low. However, a pediatric surgeon should be available in case of perforation or unsuccessful reduction.
Consider placement of a nasogastric tube if there is significant abdominal distention or bowel obstruction.
Patients must be adequately fluid resuscitated
Broad-spectrum antibiotics should be administered if there is suspicion of perforation or bowel ischemia.
Surgical reduction is indicated if there are any signs of peritonitis, or if barium or air enema does not successfully reduce the intussusception.
Intussusception will recur in up to 10% of patients.