Lower GI bleed and Mesenteric ischaemia

Question 1

Causes of mesenteric ischaemia

Answer 1

• Arterial thrombosis or embolism
• Non-occlusive: Splanchnic vasoconstriction: e.g. secondary to shock
• Venous thrombosis
• Trauma, vasculitis, strangulation

Question 2

Presentation of mesenteric ischaemia

Answer 2

• Nearly always small bowel
• Triad:
• Acute severe abdominal pain ± PR bleed
• Rapid hypovolaemia → shock
• No abdominal signs

• Degree of illness > clinical signs

Question 3

Investigations of mesenteric ischaemia

Answer 3

Bloods

• ↑Hb: plasma loss
• ↑WCC
• ↑ amylase
• Persistent metabolic acidosis: ↑lactate

• Imaging

• AXR: gasless abdomen
• Arteriography / CT/MRI ang

Question 4

Complications of mesenteric ishchaemia

Answer 4

Septic peritonitis

Question 5

Mx of mesenteric ischaemia

Answer 5

• Fluids
• Abx: gent + met
• LMWH
• Laparotomy: resect necrotic bowel

Question 6

Causes of lower GI bleeding

Answer 6

• Rectal: haemorrhoids, fissure
• Diverticulitis
• Neoplasm
• IBD
• Infection - shigella, campylobacter, salmonella
• polyps

Question 7

Investigations for lower GI bleed

Answer 7

• Bloods: FBC, U+E, LFT, G+S, clotting
• Stool: MCS
• Imaging
- AXR, erect CXR
- Angiography: necessary if no source on endoscopy
• Endoscopy
- 1st: Rigid proctoscopy / sigmoidoscopy
- 2nd: OGD
- 3rd: Colonoscopy: difficult in major bleeding

Question 8

Mx of lower GI bleed

Answer 8

• Resuscitate
• Urinary catheter
• Abx: if evidence of sepsis or perf
• PPI: if upper GI bleed possible
• Keep bed bound: need to pass stool may be large
bleed → collapse
• Stool chart
• Diet: keep on clear fluids (allows colonoscopy)
• Surgery: only if unremitting, massive bleed