Intussusception

Intussusception is telescoping of a proximal bowel segment into an adjacent distal segment, dragging its mesentery with it. Progressive venous congestion can cause bowel oedema, obstruction, arterial compromise, infarction and perforation.

Adult intussusception differs fundamentally from paediatric disease. In adults, a structural lead point is common and may be benign or malignant. Colonic intussusception carries a particularly high malignancy risk. A 2025 systematic review found malignancy in approximately 68% of colocolic and 46% of ileocolic cases, compared with about 9% of enteric small bowel cases.

Transient short segment enteroenteric intussusceptions are increasingly detected incidentally on CT and do not all require surgery.

Adults may present acutely with bowel obstruction or with intermittent symptoms over days to weeks.

Typical features are colicky abdominal pain, nausea, vomiting and distension. Gastrointestinal bleeding or a palpable mass may occur but the classic paediatric triad of pain, bloody stool and abdominal mass is uncommon in adults.

Continuous pain, focal guarding, fever, tachycardia or peritonism suggests bowel ischaemia or perforation.

An intermittent presentation with recurrent obstructive symptoms should raise suspicion for a mobile intussusception around a persistent lead point such as tumour, polyp, Meckel diverticulum or benign small bowel lesion.

CT abdomen and pelvis with IV contrast: diagnostic investigation of choice in adults; demonstrates bowel within bowel configuration and determines whether there is obstruction, a structural lead point or compromised bowel.

Check full blood count, renal function and electrolytes in obstructed patients. Add lactate and blood gas where bowel ischaemia is suspected. A normal lactate does not exclude early vascular compromise.

Colonoscopy may be useful in selected stable colonic presentations when obstruction is incomplete and malignancy needs evaluation, but should not delay surgery for threatened bowel.

Management depends on location, symptoms, lead point and bowel viability.

Immediate surgery is required for peritonitis, perforation, bowel ischaemia, complete obstruction or clinical deterioration.

Adult colonic intussusception should usually undergo oncological segmental resection without attempted reduction when malignancy is possible. Reduction risks perforation of oedematous bowel and theoretical tumour dissemination.

Small bowel intussusception is more nuanced. If the bowel is viable and imaging or operative findings suggest a benign lead point, gentle reduction can be attempted to preserve bowel length. Resect the lead point bearing segment after successful reduction. If reduction fails, bowel is compromised or malignancy is suspected, perform en bloc resection.

A short, incidental enteroenteric intussusception without obstruction, lead point or symptoms may be observed with clinical follow up rather than automatically operated upon. Recent evidence suggests short segments below approximately 3.5 cm without a lead point are particularly likely to be transient, although this threshold should support rather than replace clinical judgement.

In children, management is different. Pneumatic or hydrostatic enema reduction is first line for uncomplicated ileocolic intussusception. Peritonitis, perforation, shock, failed reduction or a pathological lead point requiring treatment mandates surgery.