Question 8

College answer

Not available.

Discussion

a) The structures supplied by each major branch are:

• Coeliac trunk:
  • Abdominal part of the oesophagus
  • Stomach
  • Superior half of the duodenum
  • Liver
  • Superior half of the pancreas
  • Spleen
• Superior mesenteric artery:
  • Intestine, from the lower half of the duodenum down to the splenic flexure of the large intestine
• Inferior mesenteric artery:
  • Colon, from the splenic flexure down to the sigmoid and superior portion of the rectum

b) Areas of intestine which are more susceptible to mesenteric arterial ischaemia:

• SMA is particularly susceptible to embolic ischaemia due to the acute angle of its take-off from the aorta and its higher blood flow rate.
• These are watershed regions which are more susceptible to non-occlusive mesenteric ischaemia (NOMI), eg. where the cardiac output is low, or where the patient is completely full of catecholamines. These are:
  • The pancreas, a watershed between the coeliac trunk and SMA
  • The splenic flexure, a watershed between the branches of the SMA and IMA

c)

The clinical scenario is said to differentiate the causes of mesenteric ischaemia, as the clinical findings are typically similar for all of them:

• Abdominal pain
• Nausea
• Vomiting
• Diarrhoea
• PR bleeding
• Peritonism

And if you wait long enough, everything starts looking like severe septic shock and multiorgan system failure. In short, the abdomen is usually the same on examination, and the way you come to the conclusion that this must be embolic or venous, is by discovering that the patient is in AF, or has recently had a bowel resection for a colonic carcinoma, or something along those lines. Because of this, the risk factors and clinical characteristics were rolled together in this tabulated response.