Makindo Medical Notes

Related Subjects: |Metabolic acidosis |Aspirin or Salicylates toxicity |Ethylene glycol toxicity |Renal Tubular Acidosis |Lactic acidosis

Ischaemic colitis usually resolves, but careful observation is essential as it can progress to gangrene, peritonitis, or stricture formation. The condition is commonly seen in older patients in their sixties to seventies.

About

• Ischaemia of the colon due to impaired blood supply.
• Inflammation and injury can range from superficial to full-thickness necrosis.
• The colon is supplied by the superior (SMA) and inferior mesenteric arteries (IMA).
• The watershed area, particularly susceptible, is the splenic flexure.

Aetiology

• Causes include thrombosis, embolism, vasculitis, spasm, and low blood flow.
• Risk factors include atrial fibrillation, atherosclerosis (e.g., atheroma in the IMA).
• Can lead to mucosal ischaemia, inflammation, necrosis, ulceration, and potential perforation.
• Often affects the splenic flexure, a watershed area between the SMA and IMA.
• Can be a complication of aortic aneurysm surgery.

Key signs include bloody bowel movements, abdominal pain, and raised WCC and lactate in older patients.

Clinical Presentation

• Crampy abdominal pain, vomiting, diarrhoea (often bloody).
• Abdominal distension, fever, tachycardia.
• In chronic cases, symptoms may include gut claudication and recurrent gastroenteritis-like symptoms.
• Localised peritonism on examination.

Complications

• Acute: Sepsis, peritonitis, perforation, toxic megacolon.
• Chronic: Stricture formation, commonly at the splenic flexure of the colon.

Investigations

• FBC: High WCC, high CRP, elevated lactate, LDH, and CK may be present.
• ABG: Metabolic acidosis with raised lactate.
• AXR: Nonspecific gas patterns or ileus, with “thumbprinting” indicating submucosal haemorrhage or oedema in advanced cases. Perforation and pneumatosis are consistent with severe injury.
• Stool culture: If diarrhoea is present and diagnosis is uncertain.
• Barium enema: In subacute presentations, may show thumb printing from submucosal swelling.
• CXR: May reveal air under the diaphragm if perforation is present.
• CT scan: Can show thickened colonic wall, intramural air, and pneumatosis or portal venous gas, suggesting bowel infarction in advanced cases.
• Colonoscopy: The diagnostic test of choice without bowel prep to assess the degree of ischaemia. Colonoscopy allows for direct visualization of mucosal changes, making it the most sensitive and specific method.

Management

• Initiate fluid resuscitation and general supportive care (ABC). Consider starting unfractionated heparin (UFH).
• Administer broad-spectrum antibiotics. Insert NG tube and provide suction if patient is nil by mouth.
• Conservative management is often effective for cases that resolve without progression.
• Surgical intervention: Required for advanced cases with complications. Involves laparotomy, resection, and exteriorisation of the affected bowel ends. Primary anastomosis is generally contraindicated. Mortality is high in these cases.