Intussusception

Intussusception is the invagination of a proximal bowel segment (the intussusceptum) into a distal one (the intussuscipiens). In children it is usually ileocolic and idiopathic, related to lymphoid hyperplasia. In adults a lead point such as a tumour is common.

Clinical presentation

Typically between 6 months and 3 years: episodes of inconsolable crying with drawing up of the legs, vomiting, lethargy and, later, redcurrant jelly stools. The full triad is present in only a minority.

Radiographic features

Ultrasound

• The test of choice, with very high sensitivity
• Target or doughnut sign in cross-section: concentric rings of bowel wall, usually in the right upper quadrant
• Pseudokidney sign in longitudinal section
• Look for trapped fluid and absent Doppler flow, which suggest ischaemia

Abdominal radiograph

May show a soft tissue mass, a crescent sign or obstruction, but a normal film does not exclude the diagnosis.

Treatment and prognosis

Image-guided pneumatic or hydrostatic enema reduction succeeds in most children. Perforation, peritonitis or failed reduction require surgery.

Differential diagnosis

• Gastroenteritis
• Acute appendicitis
• Small bowel obstruction from other causes