There are however some key differences which are highlighted in table below:
| Crohn's disease (CD) | Ulcerative colitis (UC) | |
|---|---|---|
| Features | Diarrhoea usually non-bloody | |
| Weight loss more prominent | ||
| Upper gastrointestinal symptoms, mouth ulcers, perianal disease | ||
| Abdominal mass palpable in the right iliac fossa | Bloody diarrhoea more common | |
| Abdominal pain in the left lower quadrant | ||
| Tenesmus | ||
| Extra-intestinal | Gallstones are more common secondary to reduced bile acid reabsorption | |
| Oxalate renal stones* | Primary sclerosing cholangitis more common | |
| Complications | Obstruction, fistula, colorectal cancer | Risk of colorectal cancer high in UC than CD |
| Pathology | Lesions may be seen anywhere from the mouth to anus | |
| Skip lesions may be present | Inflammation always starts at rectum and never spreads beyond ileocaecal valve | |
| Continuous disease | ||
| Histology | Inflammation in all layers from mucosa to serosa | |
| • increased goblet cells | ||
| • granulomas | No inflammation beyond submucosa (unless fulminant disease) - inflammatory cell infiltrate in lamina propria | |
| • neutrophils migrate through the walls of glands to form crypt abscesses | ||
| • depletion of goblet cells and mucin from gland epithelium | ||
| • granulomas are infrequent | ||
| Endoscopy | Deep ulcers, skip lesions- 'cobble-stone' appearance | Widespread ulceration with preservation of adjacent mucosa which has the appearance of polyps ('pseudopolyps') |
| Radiology | Small bowel enema | |
| • high sensitivity and specificity for examination of the terminal ileum | ||
| • strictures: 'Kantor's string sign' | ||
| • proximal bowel dilation | ||
| • 'rose thorn' ulcers | ||
| • fistulae | Barium enema | |
| • loss of haustrations | ||
| • superficial ulceration, 'pseudopolyps' | ||
| • long standing disease: colon is narrow and short -'drainpipe colon' |
Questions regarding the 'extra-intestinal' features of inflammatory bowel disease are common:
Antineutrophil cytoplasmic antibody (ANCA), esp. p-ANCA, is positive in UC and negative and CD.
Antisaccharomyces cerevesiae antibody (ASCA) is positive in CD and negative in UC.
All IBD is associated with anaemia and can lead to colon cancer.
Associated with increased platelet count (PLT) and plateletcrit (PCT), but decreased mean platelet volume (MPV)
According to a meta-analysis (79 studies; >21,500 participants), compared with healthy individuals, patients with IBD had a significantly higher PLT (weighted mean difference [WMD] 69.91 [62.17-77.64×109/L; p<0.001) and PCT (WMD 0.046% [0.031%-0.061%]; p<0.001). However, patients with IBD had a significantly decreased MPV (WMD −0.912 [−1.086 to −0.739 fL]; p<0.001).
Ref: https://pubmed.ncbi.nlm.nih.gov/38961334/
When should screening occur?
After 8 to 10 years of colonic involvement, with colonoscopy every 1 to 2 years.