AKT · Gastroenterology/Small bowel & malabsorption

Intestinal ischaemia

Compromised bowel blood supply (acute mesenteric ischaemia, chronic mesenteric ischaemia, ischaemic colitis)

Overview

Inadequate blood supply to the bowel. ACUTE mesenteric ischaemia (SMA embolus/thrombosis, or venous/non-occlusive) — sudden severe abdominal pain OUT OF PROPORTION to signs, an emergency with high mortality. CHRONIC mesenteric ischaemia — post-prandial pain ('gut claudication'), weight loss, food fear. ISCHAEMIC COLITIS — transient colonic ischaemia (watershed splenic flexure), bloody diarrhoea, usually self-limiting.

Recognise

ACUTE mesenteric: sudden severe central abdominal pain OUT OF PROPORTION to a soft abdomen, vomiting; AF/atherosclerosis; raised lactate, metabolic acidosis
CHRONIC mesenteric: dull post-prandial pain ('gut claudication'), weight loss, food avoidance; vascular risk factors
ISCHAEMIC COLITIS: crampy left-sided pain + bloody diarrhoea, often elderly with vascular disease; 'thumbprinting' on AXR; usually self-limiting

Red flags

Acute mesenteric ischaemia (pain out of proportion + raised lactate ± AF) → emergency surgery/revascularisation — high mortality if delayed
Peritonism/perforation; full-thickness colonic infarction

Differentials & how to tell them apart

Other acute abdomen (perforation, pancreatitis, obstruction)the 'pain out of proportion' with a soft abdomen + raised lactate points to acute mesenteric ischaemia

Infective colitisbloody diarrhoea but infective context/stool culture; ischaemic colitis is vascular/watershed

IBDyounger, chronic, endoscopic pattern

Abdominal aortic aneurysmpulsatile mass, back pain, collapse — exclude in the older patient with abdominal pain

Ischaemic colitis — mucosal oedema 'thumbprinting' of the colon (AXR/contrast)
melvil / CC BY-SA 4.0 — Wikimedia Commons

Investigations

Acute: raised lactate, leukocytosis, metabolic acidosis; CT ANGIOGRAPHY (the key test). Ischaemic colitis: CT, flexible sigmoidoscopy (mucosal ischaemia), AXR 'thumbprinting'. ECG (AF).

Management

Acute mesenteric → emergency revascularisation/resection; ischaemic colitis → supportive

1ACUTE mesenteric ischaemia: resuscitate, broad-spectrum antibiotics, urgent CT angiography and surgery/endovascular revascularisation. ISCHAEMIC COLITIS: supportive (fluids, bowel rest, antibiotics) — usually resolves.Gate: Pain OUT OF PROPORTION to examination + raised LACTATE (esp. with AF) = acute mesenteric ischaemia → emergency revascularisation; do not mistake it for a benign abdomen because the examination is unimpressive
2Resect non-viable bowel; second-look laparotomy; manage vascular risk; chronic mesenteric ischaemia → revascularisation.

Acute: resuscitation + urgent surgery/endovascular revascularisation — fluids, broad-spectrum antibiotics, resect non-viable bowel; embolectomy/revascularisation

Ischaemic colitis: supportive — fluids, bowel rest, antibiotics; usually self-limiting

Chronic: revascularisation + vascular risk management — angioplasty/stent/bypass

Key points

Sudden severe pain OUT OF PROPORTION + raised lactate + AF = acute mesenteric ischaemia (emergency). Post-prandial pain + weight loss + food fear = chronic. Bloody diarrhoea + watershed (splenic flexure) + thumbprinting = ischaemic colitis (usually self-limiting).

Monitor & prognosis

Lactate, perfusion; bowel viability.

Acute mesenteric ischaemia has high mortality; ischaemic colitis usually recovers.

Source: BSG; ACPGBI; StatPearls