Intestinal ischaemia (GI) Flashcards
Define intestinal ischaemia.
Obstruction of mesenteric vessel leading to bowel ischaemia and necrosis
What are the three types of intestinal ischaemia?
- acute mesenteric ischaemia - acute inadequate blood flow to the small intestine
- chronic mesenteric ischaemia - constant/episodic hypoperfusion of the small intestine
- ischaemic colitis AKA colonic ischaemia - hypoperfusion of the large bowel
What artery is compromised in acute mesenteric ischaemia?
Superior mesenteric artery
What is acute mesenteric ischaemia associated with? (4)
- embolism (50%) - left-sided thrombus OR from spontaneous/iatrogenic rupture and embolisation from an aortic atherosclerotic plaque/aneurysm OR atrial fibrillation
- arterial thrombosis (15-20%) - atherosclerosis at origin of SMA, can also result in subacute/chronic ischaemia
- venous thrombosis (5%) - cirrhosis/portal hypertension
- hypoperfusion (20%) i.e. non-occlusive ischaemia - shock/hypotension
What is chronic mesenteric ischaemia usually caused by?
Atherosclerosis
Which artery is usually compromised in ischaemic colitis?
Inferior mesenteric artery
Which areas are at high risk of ischaemic colitis?
- near splenic flexure
- 2/3 transverse colon at high risk due to being watershed areas
What are some risk factors associated with ischaemic colitis? (5)
- age
- AF
- smoking
- hypertension
- diabetes
Which out of the three forms of intestinal ischaemia is most common and has the most favourable prognosis?
Ischaemic colitis AKA colonic ischaemia
What forms can intestinal ischaemia present as? (3)
- transient reversible ischaemia
- chronic irreversible ischaemia
- acute fulminant ischaemia
What are the clinical features of intestinal ischaemia? (9)
- abdominal pain and tenderness:
- out of proportion to examination
- postprandial / post-exercise
- colicky
- haematochezia (fresh rectal bleeding)/melaena - ischaemic colitis
- diarrhoea
- nausea
- weight loss (chronic)
- abdominal bruits
- vasculitis
- anaemia - pallor, dyspnoea, light-headed
- food fear (sitophobia) - chronic
What is post-prandial abdominal pain AKA in chronic mesenteric ischaemia?
Intestinal angina - due to atherosclerosis
In which type of intestinal ischaemia is rectal bleeding common?
Ischaemic colitis
What is characteristic of acute mesenteric ischaemia?
Sudden, severe abdominal pain out of keeping with physical exam findings
What is the classic triad of chronic mesenteric ischaemia?
- severe, colicky post-prandial pain (intestinal angina)
- abdominal bruit
- weight loss
What are some risk factors for intestinal ischaemia? (5)
- age
- AF, MI, SHD, vasculitis, hypercoagulable states
- smoking
- diabetes
- hypertension
What are the first-line investigations for intestinal ischaemia? (5)
- CT scan with contrast / CT angiogram
- AXR
- ABG/VBG and serum lactate
- FBC
- U&Es
What does CT with contrast/CT angiogram show in intestinal ischaemia? (6)
- bowel wall thickening
- bowel dilation
- pneumatosis intestinalis (air between walls of intestine)
- portal venous gas
- occlusion of mesenteric vasculature
- bowel wall thickening with thumbprinting suggestive of submucosal oedema or haemorrhage
What does AXR show in intestinal ischaemia?
Thumbprint on barium enema for ischaemic colitis
What do we see in ABG/VBG in intestinal ischaemia?
Metabolic acidosis with high lactate
(Low HCO3-)
What might FBC show in intestinal ischaemia? (3)
- leukocytosis
- anaemia
- evidence of haemoconcentration
What might U&Es show in intestinal ischaemia?
Uraemia and elevated creatinine
What are some differential diagnoses for intestinal ischaemia? (9)
- infectious colitis (colonoscopy)
- ulcerative colitis
- Crohn’s disease (chronic diarrhoea, WL, RLQ pain)
- diverticular disease
- large bowel obstruction (can lead to ischaemia)
- small bowel obstruction (N&V, distension)
- peptic ulcer disease (epigastric, less severe)
- acute pancreatitis
- gastroenteritis
What is the management for acute mesenteric ischaemia / infarction, perforation or peritonitis on CT? (4)
- fluid resuscitation
- supportive measures - O2, NBM, NG tube with decompression
- empirical Abx
- urgent laparotomy
How do we manage a SMA embolus with infarction/perforation/peritonitis (acute mesenteric ischaemia)?
Open embolectomy or arterial bypass +/- bowel resection
How do we manage a SMA thrombosis with infarction/perforation/peritonitis (acute mesenteric ischaemia)?
Antegrade and retrograde bypass grafting, aortic re-implantation of SMA, and transarterial and transaortic mesenteric endarterectomy
How do we manage non-occlusive intestinal ischaemia with infarction/perforation/peritonitis?
Correct medical causes (heart failure), arrhythmia, shock or haemodialysis
How do we manage venous mesenteric ischaemia with infarction/perforation/peritonitis?
Anticoagulation with heparin then switching to warfarin (for 3-6 months)
Surgery indicated if infarction/peritonitis
How do we manage fulminant colitis?
Subtotal or total colectomy
How do we manage intestinal ischaemia with no evidence of infarction, perforation or peritonitis?
- SMA embolus/thrombosis = endovascular therapy (thrombolysis)
- vasculitis-associated = corticosteroid therapy - methylprednisolone
How do we manage chronic intestinal ischaemia?
- if severe malnutrition - antegrade and retrograde bypass grafting, aortic re-implantation of SMA, transarterial and transaortic mesenteric endarterectomy
- percutaneous transluminal mesenteric angioplasty alone/with stent insertion
How do we manage ischaemic colitis? (5)
- fluid resuscitation
- Abx
- conservative management
- consider anticoagulation
- consider segmental resection and stoma
What are some complications of intestinal ischaemia? (3)
- sitophobia (fear of food) –> malnutrition
- stricture
- short bowel syndrome
