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

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%

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

Location

• Always involves proximal colon, extends distally to variable degrees