Investigation | Type of investigation | Common findings in UC | Notes |
---|---|---|---|
Blood tests | Full blood count Urea and electrolytes C-reactive protein Vitamin D and bone profile Haematinics Liver biochemistry | Anaemia, thrombocytosis, low vitamin D and raised inflammatory markers | Consider pre-immunosuppressant/biologic screen in those likely to need escalation to immunosuppressant/biologic therapy (including TPMT, viral serology, quantiferon) Primary sclerosing cholangitis can be associated with UC and can present with deranged liver biochemistry |
Stool cultures | Clostridioides difficile toxin assay MC&S | Should be negative if UC, but infections such as C difficile can co-exist | Take a thorough history, including travel history to rule out other causes Recent antibiotic use may be associated with C difficile |
Faecal calprotectin | Indicates migration of neutrophils to the lumen via the intestinal mucosa | A level of 50–100 μg/g has a high negative predictive value of 98–99% in the diagnosis of IBD | Can be used as a method of monitoring treatment response |
Endoscopy | In acute setting, flexible sigmoidoscopy Ileocolonoscopy is recommended in all patients to delineate disease extent, severity of inflammation and to exclude Crohn’s disease; also for surveillance | Erythema, oedema, loss of vascular pattern, blood and ulcers/erosions | Mayo score and Ulcerative Colitis Endoscopic Index of Severity (UCEIS) score are used to assess severity of ulcerative colitis endoscopically |
Histology | Recommend at least two biopsies from each bowel segment for histological assessment | No histological features are diagnostic of UC, but basal plasmacytosis, crypt atrophy/distortion and villous surface irregularity are suggestive of UC | The presence of granulomas is more suggestive of Crohn’s disease |
Imaging | Abdominal X-ray | Thumbprinting, lead-piping, oedema and toxic megacolon | |
Imaging | Cross sectional imaging: CT/MRI | Bowel wall oedema and inflammatory pseudopolyps | Small bowel imaging can help differentiate between UC and Crohn’s disease in challenging cases |
CT = computed tomography; IBD = irritable bowel disease; MC&S = microscopy, culture and sensitivity; MRI = magnetic resonance imaging; TPMT = thiopurine methyltransferase; UC = ulcerative colitis.