24th July 2023

Investigations and diagnosis

Basic investigations for a patient presenting with suspected IBD include the following:

• Blood tests – FBC, U&Es, CRP, ESR, LFTs, haematinics, vitamin D
• Coeliac serology (for exclusion)
• Faecal calprotectin (may be raised in inflammatory bowel disease)
• Stool microscopy, culture and sensitivity

Further investigations consist of imaging and colonoscopy (with subsequent histology).
Crohn’s disease is associated with the following findings:

• Radiological:
  • Barium swallows demonstrate narrowing of lumen, features of ulceration and nodularity, and can give a “string sign” appearance in advanced disease
  • MRI with small bowel enterography (MRE) and CT with small bowel enterography (CTE) are also used
• Colonoscopy:
  • Macroscopic findings include skip lesions, cobblestone mucosa, and rectal sparing (will appear normal)
  • Microscopic findings include granulomas, focal inflammation of the lamina propria, crypt distortion

Ulcerative colitis is associated with the following findings:

• Radiological:
  • Abdominal x-ray shows proximal constipation, mucosal thickening, “thumbprinting” sign, and colonic dilation in severe disease
  • Barium enema is used to show shortening of the colon, and loss of haustra to give characteristic “lead pipe colon” appearance
  • CT and MRI show nonspecific thickening of the bowel wall, and are less sensitive compared to barium enemas for early disease
• Colonoscopy:
  • Macroscopically disease is confined to the colon and rectum, with continuous inflammation, pseudopolyps may be present
  • Microscopic findings include crypt atrophy, villous mucosa, mucin depletion and plasmacytosis