Ischaemic colitis

Develops when blood supply to colon is insufficient to meet cellular demands

Epidemiology

Low-flow state
- Shock
- CCF
Atherosclerosis
GIT
- Constipation
- Diarrhoea
- IBS
Surgery/procedures
- Abdominal surgery
- Aortic surgery - especially if IMA sacrificed
- Endovascular abdominal manipulations
- Post-colonoscopy
Cardiovascular/pulmonary
- COPD
- AF
- HTN
Metabolic/rheumatoid
- DM
- Dyslipidaemia
- SLE
- RA
Miscellaneous
- Hypercoagulable states
- Sickle cell disease
- Long-distance running
Drugs
- Anything inducing constipation (reduced blood flow and increased intraluminal pressure)
- Cocaine and methamphetamines
- Immunomodulators
- Chemotherapy
- COCP
- Serotoninergic

Disease location
- Tends to be segmental, mostly splenic area, but rectosigmoid and caecum can be involved
- Can be isolated right-sided in 25%
  - Worse prognosis, more likely to need surgery
  - More associated with IHD, CKD, AF
- Pan-colonic IC has bad prognosis
Schein says to differentiate between those comorbid (IHD, smoking, CKD) patients who get 'spontaneous' ischaemic colitis, and those who get it secondary to systemic hypoperfusion from another cause. However, isn't this the same end result, and wouldn't the former predispose to the latter, and wouldn't they be treated the same? So not a clinically significant difference.

Variable and non-specific
Sudden, cramping lower abdo pain; followed by tenesmus; haematochezia (minor)
- Present in 50% of patients
Can present with full-thickness ischaemia - high fever, leucocytosis, acidosis, peritonitis

Stool spec - specifically exclude CDI
AXR
- Thumb print - submucosal oedema - most common finding - but non-specific
- Colonic dilatation
- Mural thickening
CT
- IV/PO contrast
- Should probably do multi-phase scan to exclude acute mesenteric ischaemia if indicated
Flexi sig is gold standard
- No increased risk of perforation, but refrain from over-insufflation, and no need to go further than the pathology
- Can't usually distinguish between partial and full thickness ischaemia
- Ulceration/ischaemic changes
- Single stripe sign is believed to be specific
- Mild: mucosal oedema, erythema, petechial haemorrhage, mucosal ulceration, firm mucosa on biopsy
- Severe: dusky mucosa, submucosal haemorrhage, haemorrhagic ulcerations that can progress to frank necrosis
- Abrupt cut-off to normal mucosa is typical

- Although I think many in Australia would disagree about the need for endoscopy if reassuring presentation
Medical
- Bowel rest
- IVF resuscitation
- Antibiotics (to cover for translocation)
- Optimise underlying causes
If no improvement within a few days, repeat the imaging or perform flexi sig
Surgery
- Absolute indications
  - Peritonitis
  - Pneumoperitoneum
  - Massive haemorrhage
  - Signs of transmural necrosis
  - Failing medical treatment
- Operation
  - Laparotomy
  - Exploration of entire small and large bowel
  - Segmental resection (anatomically) with either an end ileostomy or end colostomy
  - Can staple ends and do second-look laparotomy
- Elective surgery
  - Consider it for recurrent episodes of colitis and pain, or stricture