Early identification and treatment of intussusception critical for young patients

By Dave R. Lal, MD, and John Densmore, MD

Intussusception occurs when one portion of the small bowel (intussusceptum) peristalses into the lumen of a downstream portion (intussuscipiens) much like a collapsing telescope. Once this prolapse has occurred, lymphatic and venous drainage of the intussusceptum is impaired. This results in edema, strangulation, ischemia and ultimately necrosis if the intussusception persists. Additionally, the lumen of the intussuscepted portion of bowel collapses, causing intestinal obstruction. 

Intussusception is the most common cause of intestinal obstruction in children younger than age 2. Infants and children 3 months to 3 years are most commonly affected with a peak incidence between 4 and 10 months^1-3. Intussusception occurs nearly twice as often in boys as in girls.

Pathophysiology

Only 10 percent of pediatric intussusception can be attributed to a gross pathologic lead point. The most common lead points include Meckel's diverticulum, intestinal polyp (Peutz-Jegher syndrome), intestinal duplication, hemangioma, suture line, appendix, tumors (lymphoma) and ectopic pancreas. These lead points should be suspected in children older than age 2 with intussusception and those with classic symptoms and normal contrast enema (ileo-ileal intussusception)³. 

Intussusception is idiopathic in 90 percent of pediatric cases. A vast majority of these are the ileocolic type that results when a segment of ileum (intussusceptum) enters the colon (intussuscipiens). Viral gastroenteritis (most commonly adenovirus), Henoch-Schönlein purpura, intestinal lymphyoid hyperplasia and meconium ileus all have been associated with intussusception via subtle lead points. An association between intussusception and the tetravalent live attenuated rotavirus vaccine was identified in 1999². Newer, oral attenuated rotavirus vaccines licensed in 2006 – the pentavalent bovine-human reassortant vaccine (RotaTeq) and the monovalent human rotavirus vaccine (Rotarix) – are not associated with increased risk of intussusception⁴. Lymphoid hyperplasia, mesenteric adenitis and Peyer patch hypertrophy may result in recurrent intussusception without mucosal irregularity visualized on contrast reduction studies⁵.

Clinical presentation

Figure 1 Diaper demonstrating current jelly stool. Photo courtesy of Andrea Winthrop, MD.

Intussusception should be included in the differential diagnosis of all children with intestinal obstruction. The early presenta-tion is marked by sudden onset of severe paroxysms of abdominal pain. The child appears normal between episodes. Infants manifest these symptoms as sudden crying with flexed hips and knees interspersed with periods of calm. Vomiting and evacuation of the distal intestine follow later in the course as obstruction develops. Lethargy and pallor may be significant and out of proportion to abdominal signs in infants with intussusception. A sausage-like mass may be palpated on abdominal exam in some cases. Eventually, mucosal ischemia results in the passage of "currant jelly stools" comprised of bloody sloughing mucosa. (See Figure 1.) Late in the course, focal or diffuse peritonitis may result due to necrosis and perforation.

Diagnostic evaluation and treatment

Initial evaluation of the child with a nonspecific presentation of vomiting and possible gastrointestinal obstruction should include an abdominal radiograph. While this study may miss the diagnosis of intussusception very early after presentation, positive findings of an intussusception – such as proximal bowel dilation, distal air outlining the intussusceptum or intraperitoneal air – can be found in 74 percent of cases. Cross-sectional ultrasonography of the intussusception reveals a "target" sign with concentric layers of serosa and mucosa. The diagnostic accuracy for ultrasound is approximately 85 percent¹. A target sign also may be visible on abdominal CT scan with IV contrast.

Figure 2a Contrast enema in a patient with ileocolic intussusception. Contrast demonstrates intussusception extending to the splenic flexure.

Patients with a typical presentation in whom the clinical suspicion of intussusception is high may avoid other radiological tests and proceed directly to a contrast study. Prior to the study, it is imperative that the child be adequately volume resuscitated. Radiographic contrast enemas (air or hydrostatic) have the advantage of being diagnostic and potentially therapeutic. (See Figure 2a and 2b.) The overall success rate with hydrostatic reduction is reported to be 79 percent and up to 90 percent with air contrast enema⁶. Both methods may result in bowel perforation so surgical consultation should precede reduction attempts. Most patients are managed as outpatients after successful nonoperative reduction and demonstration of feeding tolerance⁷. These enema techniques may miss an ileoileal or more proximal intussusception.

Presence of peritonitis and evidence of perforation are contraindications to non-operative management. Three to 15 percent of reduced children relapse after successful radiographic reduction^{1, 7, 8}. A repeat contrast enema may be attempted safely. Failure should result in surgical reduction after appropriate resuscitation and prophylactic antibiotic administration. 

Figure 2b Contrast enema in a patient with ileocolic intussusception. Successful hydrostatic reduction with contrast refluxing into the distal small bowel.

The surgical management of intussusception begins with attempts at manual reduction. If reduction is successful and no pathologic lead point is identified, the operation is concluded. Because the standard intussusception incision is in the right lower quadrant and is similar to an appendectomy incision, the appendix is removed to avoid future confusion. In cases of perforation, necrosis, pathologic lead point or inability to reduce the prolapsed segment, a bowel resection and primary anastomosis is performed.

Conclusion

Intussusception is the most common cause of bowel obstruction in children younger than age 2. Rapid diagnosis and treatment is necessary to avoid bowel ischemia and ultimately perforation. Initial management includes fluid resuscitation, surgical consultation and attempted reduction by radiographic contrast (hydrostatic or air) enema. Failure to reduce the intussusception requires operative intervention.