Ischaemic colitis

• Overview:

  • Most common form of intestinal ischaemia
  • Typically a disease of the elderly
  • Decreased blood flow to segment of large bowel - usually transient, causes mucosal ulceration, inflammation and haemorrhage
  • Can span a wide spectrum of severity - most have transient decrease in intestinal perfusion but a minority have prolonger hypoperfusion which can result in severe ischaemia
  • Signs and symptoms reflect severity of disease
• Presentation:

  • Crampy abdominal pain in affected segment (often left side)
  • Urgency
  • Bright blood PR (bleeding late sign in AMI)
  • PR bleeding often mixed with diarrhoea
  • Abdominal tenderness (late sign in AMI)
  • Often the cause has resolved by the time it's diagnosed
• Cause:

  • Reduced blood flow resulting in bowel wall ischaemia and secondary inflammation
  • Many things can affect blood flow to the colon temporarily - often cause has resolved by the time it is diagnosed
  • Normally happens in elderly people with extensive comorbidities and cause is multifactorial
  • Unlike AMI it is rare to have occlusion that solely affects the colon
  • Usually non-occlusive cause (reduced perfusion) affecting watershed regions
• Watershed regions:

  • Splenic flexure
  • Rectosigmoid junction
• Risk factors for non-occlusive colonic ischaemia:

  • Heart failure (low output state)
  • Septic shock
  • Peripheral vascular disease
  • Following cardiovascular surgery (clamping of vessels and decreased gut perfusion during surgery)
• Blood supply to colon:

  • Many branches supply the colon and most areas of the colon receive blood supply from multiple branches
  • Most of the colon has collateral supply - marginal artery of Drummond
  • There are 2 watershed areas in the colon where there is not good collateral supply making these areas of bowel vulnerable - splenic flexure and rectosigmoid junction
• Investigations:

  • Bedside - observations, ECG
  • Bloods - FBC, U+Es, CRP, clotting, LFTs, G+S (tend to see raised WCC and inflammation markers)
  • ABG - to asses for metabolic acidosis and raised lactate
• Imaging:

  • CT abdomen/pelvis with contrast will show signs of ischaemia:
  • Bowel dilatation and thickening
  • Surrounding fat stranding or free fluid
  • Gangrene and perforation if severe
• Special tests:

  • Colonoscopy - direct visualisation of bowel and biopsy to help confirm diagnosis
  • Findings depend on severity of ischaemia and can range from mild patchy haemorrhages to extensive necrosis
  • Usually sharply defined segment of involvement in left colon in the watershed area
  • Risk of perforation undertaking colonoscopy on ischaemic bowel
• In stable patients - abdominal CT +/- endoscopy

  Unstable patients with acute abdomen - emergency surgery
• Management:

  • Majority of patients are stable and supportive treatment is sufficient
  • Usually self resolving and no need for surgery
  • Supportive management - analgesia, NBM, IV fluids and broad spectrum antibiotics
  • Treat any underlying condition e.g. HF
  • If occlusive try to revascularize but this is rarely the case
  • Unstable disease with severe ischaemia - may need surgery and ITU