Intestinal Ischaemia

Question 1

What are the main types of intestinal ischaemia

Answer 1

Acute mesenteric: occlusion of an artery supplying the small bowel e.g. SMA
Chronic mesenteric
Ischaemic colitis: transient compromise in blood flow to the large bowel

Question 2

Differences between mesenteric ischaemia and ischaemic colitis

Answer 2

Mesenteric:
- Typically small bowel
- Due to embolism
- Sudden onset and severe
- Requires urgent surgery
- High mortality

Ischaemic colitis
- Large bowel: watershed area
- Transient, less severe symptoms + blood diarrhoea
- Thumbprinting
- Conservative management

Question 3

Aetiology of intestinal ischaemia

Answer 3

Arterial:
- Embolism - atherosclerosis, heart thrombus, AF
- Thrombosis - atherosclerosis at the SMA
- Vasculitis e.g. RhA, polyarteritis nodosa, SLE, Takayasu’s arteritis
- External compression e.g. coeliac axis compressed by the median arcuate ligament of the diaphragm OR tumours/masses

Venous:
- thrombosis of the superior mesenteric vein
- Associated with cirrhosis or portal HTN
- Seen in hypercoagulable disorders

Hypoperfusion: occlusive (20%):
- Shock, hypotension
- HF
- Dialysis
- Recent surgery/traum
- Infection

Question 4

Anatomy of intestinal ischaemia

Answer 4

The small intestine receives blood via the coeliac artery and the superior mesenteric artery (SMA)
The colon receives blood via the SMA and the inferior mesenteric artery (IMA)
The rectum also receives blood via branches of the internal iliac artery.

The splenic flexure and the recto-sigmoid junction are two watershed areas where collateralisation of blood flow may be limited.
the regions of the intestine with a solitary arterial supply, and the watershed areas, are both at increased risk of developing ischaemia

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)

Obs: Fever, Tachycardia

Abdominal tenderness
Distensions
Peritonitis
Abdominal bruit

Question 9

Investigation for Intestinal Ischaemia

Answer 9

First line: CT with contrast
- Bowel wall thickening
- bowel dilation
- pneumatosis intestinalis
- portal venous gas
- mesenteric vasculature occlusion
- THUMB PRINTING
CT angiography
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

ECG: AF< arrhythmia, MI

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

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

Question 10

Management for acute mesenteric ischaemia

Answer 10

Supportive:
- IV fluids
- NBM + NG tube
- ABx
- Treat underlying cause

Infarction, perforation, peritonitis → immediate laparotomy
- Embolus → open embolectomy
- Arterial bypass ore reconstruction
- Bowel resection

Stable → endovascular repair or anticoagulation

Follow up → Colonoscopy follow-up (assess recovery or stricture formation)

Question 11

Management for ischaemic colitis

Answer 11

usually supportive
- IV fluids
- NBM + NG tube
- ABx
- Treat underlying cause

Surgery may be required in a minority of cases if conservative measures fail. Indications would include generalised peritonitis, perforation or ongoing haemorrhage → colectomy

Question 12

Complications for intestinal ischaemia

Answer 12

Gangrene
Perforation
Sepsis
Toxic megacolon
Pyocolon
Segmental UC
Stricture formation

Question 13

Prognosis for intestinal ischaemia

Answer 13

Depends on extent and timing of ischaemic insult and comorbidities
Most settle with conservative treatment
Acute mesenteric ischaemia has poor prognosis, especially if the surgery is delayed (mortality 60-100%)