Definition

- Ischaemic necrosis of a segment of the small intestine.

Epidemiology

- Usually seen in patients aged >50 y.

Aetiology

- Thrombosis overlying an unstable atherosclerotic plaque in the superior mesenteric artery.

- Thromboemboli from the left ventricle or left atrium.

- Hypovolaemia.

Pathogenesis

- Sudden reduction in blood flow through the superior mesenteric artery leads to ischaemic necrosis of a segment of the small bowel.

- Massive haemorrhage into the infarcted bowel causes hypovolaemia.

- Bacteria rapidly permeate the devitalized intestinal wall, leading to sepsis.

Presentation

- Acute onset of severe abdominal pain with bloody diarrhoea and hypovolaemia.

Macroscopy

- The infarcted small bowel appears dusky purple (Fig. 7.3).

- On opening the segment of bowel, large amounts of blood are present in the lumen and the mucosal surface is friable and necrotic.

Histopathology

• Full-thickness necrosis of the bowel wall. Milder changes include crypt atrophy (withering).

Prognosis

- Early laparotomy is essential to resect the infarcted segment of bowel.

-Survival is generally poor due to the rapid development of hypovolaemia and sepsis, causing multiorgan failure.