Acute colonic ischaemia

Acute colonic ischaemia, also called ischaemic colitis, is the most frequent form of intestinal ischaemia, although also a disorder of elderly. Although it is more frequent than small intestinal ischaemia, it is less deadly, as the colon handles ischaemia better than the small intestine. In 80% of cases it is mild, the so-called nongangrenous form. In the remaining cases however, it is severe and causes colonic gangrene.

Colonic ischaemia mostly occurs at the “watershed” areas of the colon, as these areas has the poorest perfusion. The splenic flexure and rectosigmoid junction are watershed areas; thus, the left colon is mostly affected.

Many conditions may predispose to acute colonic ischaemia, and in some cases no specific cause is identified:

• Mesenteric arterial or venous occlusion
• Myocardial infarction
• Hypotension
• Diabetes mellitus
• Abdominal aortic aneurysm repair
• Drugs
  • Constipation-inducing drugs
  • Immunomodulator drugs (anti-TNF, interferon)
  • Illegal drugs

Clinical features

Patients usually have mild abdominal pain and tenderness over the left colon, as well as rectal bleeding or bloody diarrhoea.

Diagnosis

The diagnosis may be made clinically, in the context of typical history, physical examination, and clinical features. Abdominal CT with contrast is usually the initial study in patients with suspected intestinal ischaemia. Although there are no specific findings for colonic ischaemia on CT, it will exclude other differential diagnoses.

Colonoscopy confirms the diagnosis, and shows an oedematous, friable mucosa with erythematous and pale areas. Histology by biopsy shows necrotic changes.

Treatment

Supportive care, nil per mouth, and broad-spectrum antibiotic therapy should be performed in all cases. In mild and moderate cases, these measures are usually enough. If due to a treatable etiology like vessel occlusion, these should be treated.

In severe, gangrenous cases, laparotomy with segmental resection is necessary.