acute mesenteric ischaemia

Question 1

what is acute mesenteric ischaemia?

Answer 1

the sudden decrease in blood supply to the bowel, resulting in bowel ischaemia and if not promptly treated, rapid gangrene and death

Question 2

what are the common causes of acute mesenteric ischaemia?

Answer 2

• thrombus in situ (acute mesenteric arterial thrombosis) e.g atherosclerosis
• embolism (acute mesenteric arterial embolism) e.g Cardiac causes/ Abdominal or thoracic aneurysm
• non occlusive cause (non occlusive mesenteric ischaemia) e.g hypovolemic or cardiogenic shock
• venous occlusion and congestion (mesenteric venous thrombosis) e.g coagulopathy, malignancy, inflammatory disorders

Question 3

what are the risk factors for acute mesenteric ischaemia?

Answer 3

depend on underlying cause

specifically for acute mesenteric arterial thrombosis, main reversible risk factors are

• smoking
• hyperlipidaemia
• hypertension

other potential causes are

• AF
• intracardiac thrombus
• thoracic aneurysm/ thrombus

Question 4

what are the clinical features of acute mesenteric ischaemia?

Answer 4

• generalised abdominal pain out of proportion to clinical factors
• diffused. constant pain
• nausea an dvomitting
• examination may be unremarkable and patient can’t localise pain
• late stage ischaemia and necrosis can present as bowel perforation
• take note of embolic sources e.g AF, heart murmurs, or signs of previous valvular replacement surgery

Question 5

what are the differentials for acute mesenteric ischaemia?

Answer 5

• peptic ulcer disease
• bowel obstruction
• symptomatic AAA

Question 6

what lab tests are done for acute mesenteric ischaemia?

Answer 6

• ABG to asses acidosis and serum lactate, secondary to bowel infarction
• routine bloods (FBC, U&E, clotting, amylase, LFTs and group and save)

NB: As well as in pancreatitis, amylase also rises in mesenteric ischaemia, as well as ectopic pregnancy, bowel perforation and DKA

Question 7

what can cause a risk in amylase?

Answer 7

As well as in pancreatitis, amylase also rises in mesenteric ischaemia, as well as ectopic pregnancy, bowel perforation and DKA

Question 8

what imaging can be done for acute mesenteric ischaemia?

Answer 8

• CT scan with IV contrast
• arterial bowel ischaemia will show on CT imaging as an oedematous bowel, secondary to ischaemia and vasodilation, before progressing to loss of bowel wall enhancement and pneumatosis
• suspicion of bowel perforation = erect CXR for evidence of perforation and CT abdomen with IV contrast

(avoid oral contrast in mesenteric ischaemia due to difficulty in assessing bowel wall enhancement)

Question 9

what is the initial management for acute mesenteric ischaemia?

Answer 9

a surgical emergency

requires urgent resuscitation and early senior involvement

• IV fluids
• catheter
• fluid balance chart
• broad spectrum antibiotics due to risk of faecal contamination in cases of perforation of the ischaemic or necrotic bowel and bacterial translocation
• early ITU input due to significant acidosis

Question 10

what is the definitive management for mesenteric ischaemia?

Answer 10

• excision of necrotic or non viable bowel if no viable revascularisation.
  Most patients will end up with a covering loop or end stoma.
• revascularisation of the bowel. Removes thrombus via radiological intervention. Preferably done via angioplasty.

Question 11

what are the complications from acute mesenteric ischaemia?

Answer 11

bowel necrosis and perforation

post surgically, may get short gut syndrome,a malabsorption disorder caused by a lack of functional small intestine.