Intestinal Ischaemia

Question 1

Definition of bowel ischaemia

Answer 1

A reduction in blood flow through the mesenteric vessels due to either occlusive or non-occlusive causes. This would lead to bowel ischaemia

Question 2

Aetiology of bowel ischaemia

Answer 2

• Split into:
‣ ACUTE MESENTERIC ISCHAEMIA:
◦ Primarily affects the small bowel
◦ Main cause is usually OCCLUSIVE due to thromboembolism (AF is a big risk factor)
◦ Sudden onset
◦ However, the abdominal pain is OUT OF PROPORTION compared with clinical signs
◦ Likely affecting superior mesenteric artery

	‣ ISCHAEMIC COLITIS:
						◦ Primarily affects the large bowel 
						◦ Usually due to NON-OCCLUSIVE LOW FLOW STATES through the inferior mesenteric artery 
						◦ More likely to occur in areas such as the splenic flexure (less well supplied)
						◦ More mild and gradual onset

Question 3

Risk factors for bowel ischaemia

Answer 3

‣ Age >65 years old
‣ Cardiac arrhythmias (mainly AF)
‣ Atherosclerosis
‣ Hypercoagulation/thrombophilia
‣ Vascularised
‣ Sickle cell disease
‣ Profound shock causing hypotension

Question 4

History and examination of bowel ischaemia

Answer 4

• Abdominal pain:
◦ Acute onset, crampy pain
◦ Abdo pain is out of proportion to examination in acute mesenteric Ischaemia
◦ May worsen after eating
• Abdominal tenderness
• Bloody, loose stool (currant jelly stools)
• Fever, signs of septic shock: if perforated

Question 5

Investigations for bowel ischaemia

Answer 5

• CTAP with contrast/CT angiogram: Would be able to detect disrupted flow and vascular stenosis. Can visualise colonic thickening, bowel dilation, pneumatosis intestinalis and thumbprint sign (unspecific sign of colitis)
• FBC: Many patients will have neutrophilic leukocytosis
• ABG with lactate: likely to see lactic acidosis due to ischaemia
• Endoscopy/colonoscopy: for mild-moderate cases

Question 6

Treatment of bowel ischaemia

Answer 6

CONSERVATIVE (usually only for ischaemic colitis):
• IV fluid resuscitation, NBM, broad spectrum antibiotics (cover for sepsis), NG tube for decompression and anticoagulation (usually heparin)
• Treat underlying cause

SURGICAL MANAGEMENT (small bowel Ischaemia, infarction, perforation etc):
^all of the above
1) Exploratory laparotomy: Resect the necrotic bowel and consider open embolectomy/mesenteric arterial bypass
Can consider Endovascular revascularisation

Question 7

Prevention and prognosis of bowel ischaemia

Answer 7

• Manage CVD risk factors and treat underlying conditions
• Smoking cessation, statin and anti-platelet or anti-coagulant

Poor outlook for acute mesenteric ischaemia patients (high mortality rates)
Diagnosis before infarction increases chance of survival
Ischaemic colitis has the most favourable prognosis but it is still poor

Question 8

Complications of bowel ischaemia

Answer 8

• Short bowel syndrome: due to bowel resection
• Sepsis
• Perforation