• Telescoping of 1 segment of bowel onto adjacent section leading to vascular insufficiency, bowel wall edema, & possibly infarct. Most common at ileocecal junction
• Can be assoc w/ a “lead point” (3–10%); mass, lymphoid tissue, Meckel diverticulum, etc.
Epidemiology (Pediatrics 2011;127:e296)
• Most common cause of intestinal obstruction in infants and young children. Most common age 5–9 mo but can occur at any age. 67% occur by 1 yo
• ↑ risk w/ age >5 mo, males and those who p/w lethargy, bilious vomiting, and no diarrhea
• Prior rotavirus vaccine (RotaShield) withdrawn 2/2 concern for assoc w/ intussusceptions
• RotaTeq (pentavalent) and Rotarix (monovalent) vaccines w/ good safety/efficacy profiles in large trials; no ↑ risk of intussusception w/ use of these new vaccines.
Clinical Manifestations (Arch Pediatr Adolesc Med 2000;154:250)
• Classically p/w intermittent abd pain (pulling legs up to abd), abd mass (classically sausage-shaped mass in RLQ) and bloody stool (classically currant jelly stools); in reality this triad seen in <50% of patients
• Can p/w just lethargy, usually late in course, but can be early, especially w/ infants
• Often w/ Hx of recent viral infection and higher incidence in spring and autumn
Diagnostic Studies and Management (Clin Radiol 2005;60:39; Pediatr Radiol 2009;39:S140)
• Primarily dx ’d on radiography, but need high index of suspicion, check stool guaiac
• Plain abdominal radiographs: May be nml or may show frank obstruction w/ dilated loops, rarely (if perforated) free air. May see “target” sign (intussusceptus) over R kidney or “crescent” sign (intestinal gas trapped btw two intussuscepted surfaces). Absence of bowel gas in ascending colon is very specific. If plain film positive, proceed to ultrasound or air enema. If negative, age >5 mo, absence of bilious emesis, and presence of diarrhea → can be observed
• Ultrasound: w/ 98–100% sensitivity and 88–100% specificity in experienced hands
• May see “target” sign or “pseudokidney” sign w/ several concentric rings; can be operator dependent though. Also Doppler blood flow does not correlate w/ necrosis
• Contrast (barium or H2O soluble agent) or air enema: Diagnostic and therapeutic but w/ small risk (0–3%) perforation (lower w/ air); discuss w/ pediatric surgery if available
• Contrast or air enema results in reduction of intussusception 55–95%; if not, need surgery