Ileocolic Intussusception



  • Invagination of distal small bowel (intussusceptum) into colon (intussuscipiens) in telescope-like manner


  • US: Best diagnostic modality if clinically suspected

    • Round mass with target sign in right abdomen

    • Mean diameter of 2.6 cm (vs. 1.5 cm for purely small bowel intussusceptions)

    • Sweeping transducer proximal & distal shows relationship to small & large intestine

    • May see entrapped lymph nodes, appendix, other pathologic lead points (such as duplication cyst)

    • Entrapped fluid: ↑ failure rate of enema reduction

    • ↓ vascularity associated with ↑ likelihood of bowel necrosis & ↑ failure rate of reduction

  • Radiography: Often abnormal, not always perceived

    • Paucity of right abdominal colonic gas ± round mass

      • ± fat density (from entrapped mesentery) in mass

    • Crescent sign: Curvilinear mass-gas interface

    • Lateralization of ileum to expected cecal location

    • ± small bowel obstruction

  • Air enema reduction: Rush of air into small bowel → success

Clinical Issues

  • Most common from ages 3 months to 3 years

    • ∼ 90% idiopathic; ∼ 5-10% from lead points (Meckel diverticulum > duplication cyst > polyp > lymphoma)

  • Presentation: Lethargy & irritability, colic, crampy abdominal pain, intermittent fussiness, palpable right-sided abdominal mass, “currant jelly” stools, vomiting (may be bilious)

  • Treatment: Urgent as bowel can infarct if not reduced

    • Reduction: Air enema under fluoroscopy vs. hydrostatic with US guidance

    • Surgery if enema fails or contraindicated

    • Recurs after reduction in ∼ 5-15%

Coronal graphic shows an ileocolic (IC) intussusception with the terminal ileum invaginating into the cecum & ascending colon. Note the vascular congestion of the intussusceptum.

Photograph from an intraoperative IC intussusception reduction (after a failed air enema reduction attempt) shows the distal ileum
invaginating into the cecum

AP radiograph shows a typical case of IC intussusception with a right upper quadrant soft tissue mass
overlying the hepatic flexure. Note the lateralization of ileum
into the right lower quadrant.

Transverse power Doppler US of the right lower quadrant in this 1 year old with abdominal pain shows the classic target sign of intussusception
. The target is composed of the various bowel wall layers of the intussuscipiens & intussusceptum as well as intervening fat.



  • Invagination of distal small bowel (intussusceptum) into colon (intussuscipiens) in telescope-like manner


General Features

  • Location

    • Always involves proximal colon, extends distally to variable degrees

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