Intestinal Ischaemia

Question 1

Define Intestinal Ischaemia

Answer 1

Group of disorders resulting in ischaemia due to insufficiency blood flow to the GI tract

Question 2

What are the 3 main conditions of intestinal ischaemia

Answer 2

Acute mesenteric: Embolism that occludes an artery supplying the small bowel e.g. SMA, severe sudden pain + normal exam
Classically - patients with AF

Chronic mesenteric: rare “intestinal angina”, colicky intermittent pain

Ischaemic colitis: acute + transient compromise to blood flow -> inflammation, ulceration, haemorrhage. Most likely to occur in the watershed areas e.g. splenic flexure / recto-sigmoid junction

Question 3

Aetiology of Intestinal ischaemia

Answer 3

Arterial: embolism from LA (AF), thrombosis in SMA, vasculitis (RA, SLE), external comrpession

Venous thrombosis (SMA) ass. with cirrhosis of portal HTN / hyper coagulability

Hypoperfusion (non-occlusive ischaemia): shock, hypotension - heart failure, dialysis, drugs, surgery, infection

Question 4

Risk factors of Intestinal Ischaemia

Answer 4

Old age 
Atrial fibrillation (mesenteric)
Smoking
Hyper-coagulable states
MI 
IBS 
Structural heart defect
Hx of vasculitis

Question 5

Symptoms of Intestinal Ischaemia

Answer 5

Abdominal pain (varies according to bowel affected, out of proportion to exam)
Haematochezia/melaena (mucosal sloughing -> blood loss)
Diarrhoea
Fever
Anaemia: light headed, dizziness, pallor, dyspnoea
Weight loss (chronic)

Question 6

How does site of pain relate to type of intestinal ischaemia

Answer 6

Mainly right sided: acute mesenteric

Post-prandial and colicky pain: chronic

Left Lower quadrant: ischaemic colitis

Question 7

What is the acute mesenteric ischaemia triad

Answer 7

Abdominal pain
Hypovolaemic shock
Normal abdominal exam

Question 8

Signs of Intestinal ischaemia on examination

Answer 8

Often normal exam (acute mesenteric)

May be:
Abdominal tenderness
Distensions
Local peritoneum 
Fever
Tachycardia
Abdominal bruit
Vasculitis signs

Question 9

Investigation for Intestinal Ischaemia

Answer 9

CT with contrast/CT angiogram: bowel wall thickening | bowel dilation | pneumatosis intestinalis | portal venous gas | mesenteric vasculature occlusion | THUMB PRINTING
Sigmoidoscopy/colonoscopy + biopsy (colonic ischaemia): Mucosal sloughing, petechiae, friability | submucosal haemorrhage nodules, erosions, ulcerations, oedema | luminal narrowing | necrosis, gangrene
Mesenteric angiography: definitive for mesenteric ischaemia

VBG: lactic acidosis, elevated lactate
FBC: leukocytosis, anaemia
CRP: raised
Coagulation panel: check for underlying coagulopathy

ECG: AF< arrhythmia, MI

Erect CXR: pneumorperitoneum in perforation
AXR: Air-fluid levels | bowel dilation | bowel wall thickening | pneumatosis | gasless abdomen/white out (mesenteric) OR Thumb printing (ischaemic colitis)
Mesenteric duplex USS: reduced or lack of blood flow in vessels
MR angiography: narrowing or obstruction of mesenteric vasculature