John C. Densmore and Dave R. Lal
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 under 2 years of age. Infants and children aged 3 months to 3 years are most commonly affected, with a peak incidence between 4 and 10 months (Fig. 404-1).1-4 Intussusception occurs up to twice as often in boys as in girls and has an incidence of 25 to 50 cases per 100,000 in the first year of life.1,2,5
Only 10% of pediatric intussusception can be attributed to a gross pathologic lead point. The most common lead points include Meckel 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 over 2 years of age with intussusception and in those with classic symptoms and normal contrast enema (ileoileal intussusception).4
Intussusception is idiopathic in 90% of pediatric cases. A vast majority of these cases are the ileocolic type that results when a segment of ileum (intussusceptum) enters the colon (intussuscipiens) (Fig. 404-2). Viral gastroenteritis (most commonly adenovirus), Henoch-Schönlein purpura, intestinal lymphoid hyperplasia, and meconium ileus have all been associated with intussusception via subtle lead points. An association between intussusception and the tetravalent live attenuated rotavirus vaccine was identified in 1999.2 Newer, oral attenuated rotavirus vaccines were licensed in 2006: The pentavalent bovine-human reassortant vaccine (RotaTeq) and the monovalent human rotavirus vaccine (Rotarix) are not associated with increased risk of intussusception.8 Lymphoid hyperplasia, mesenteric adenitis, and Peyer patch hypertrophy may result in recurrent intussusception without mucosal irregularity visualized on contrast-reduction studies.9
FIGURE 404-1. Age distribution of all intussusception cases (n = 288). (From Buettcher M, Baer G, Bonhoeffer J, et al. Three-year surveillance of intussusception in children in Switzerland. Pediatrics. 2007;120:473-80.)
Intussusception should be included in the differential diagnosis of all children with intestinal obstruction (see Chapter 389). The early presentation 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 such that they often undergo evaluation for sepsis or meningitis before the correct diagnosis is recognized. eTable 404.1 shows the most common signs and symptoms and their frequencies.1 A sausagelike mass may be palpated on abdominal exam in some cases. Eventually, mucosal ischemia results in the passage of “currant jelly stools” comprising bloody sloughing mucosa. Late in the course, focal or diffuse peritonitis may result due to necrosis and perforation.
FIGURE 404-2. Ileocolic intussusception. (From Ziegler M, Azizkhan R, Weber T (eds). Operative Pediatric Surgery. New York: McGraw-Hill, 2003, p. 648.)
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% 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%.1 A target sign may also be visible on abdominal CT scan with IV contrast.
Patients with a typical presentation in whom the clinical suspicion of intussusception is high may avoid other radiologic 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. The overall success rate with hydrostatic reduction is reported to be 79%, even in children with more than 24 hours of symptoms.5 Success rates of up to 90% are reported with air contrast enema.10 Both methods may result in bowel perforation, so surgical consultation should precede reduction attempts. These enema techniques may miss an ileoileal or more proximal intussusception. Most patients (65%) are managed as outpatients after successful nonoperative reduction and demonstration of feeding tolerance.11 Presence of peritonitis and evidence of perforation are contraindications to nonoperative management. Following successful reduction, 3% to 15% of children have a recurrence of intussusception.1,5,11 A second attempt may be safely completed within a few hours. Failure at this attempt should result in surgical reduction after appropriate resuscitation and prophylactic antibiotic administration.
The surgical management of intussusception begins with attempts at manual reduction. If reduction is successful and no pathologic lead points are identified, the operation is concluded. In cases of perforation, necrosis, pathologic lead point, or inability to reduce the prolapsed segment, a bowel resection and primary anastomosis are typically performed.
COMPLICATIONS AND OUTCOMES
Prompt diagnosis and nonoperative reduction of intussusception is associated with a marked reduction in morbidity and mortality over the last century.12 In a prospective Swiss series of 288 children with intussusception diagnosed between 2003 and 2006, 13% of cases reduced spontaneously, 63% were hydrostatically reduced, 23% required surgical intervention, and there was no associated mortality.1 The use of selective surgical intervention and improved operative techniques allows for an overall mortality of less than 1% in current series.6