Differences between Crohn’s Disease and Ulcerative Colitis

FactorCrohn’s DiseaseUlcerative Colitis
DistributionAffects small bowel and large bowelAffects large bowel only
Rectum frequently spared
Inflammation not continuous (presence
of skip lesions)
Bowel wall is thickened and has a ‘cobblestoned’
appearance due to deep ulcers and swelling
of the tissue
Rectum always affected
Inflammation is uniform

Bowel wall is thin with loss of vascular pattern
(blood vessels not visible)
RadiologyStrictures are common
Deep fissures and fistulae are common
Asymmetrical inflammation
Strictures and fissures are much less common in UC
Symmetrical inflammation
HistologyPresence of granulomas are almost diagnostic
Inflammation extends through the mucosa and
muscle of the bowel
The increase in white cells tend to be lymphocytes
Granulomata absent
Inflammation usually confined to mucosa

The increase in white cells tend to be polymorphs
DietRemission achieved with enteral feed followed by
exclusion/ elimination diet
Unaffected by diet
Patients often thin and may be malnourished due to
intestinal malabsorption of nutrients
Diarrhoea – only sometimes with blood
Abdominal mass common
Weight loss usually related to the severity of
active disease
Bloody diarrhoea
Abdominal mass uncommon
SmokingStrongly associated with smoking
Predicts a worse course of disease
Increases risk of surgery & further surgery
Associated with non-smokers or ex-smokers
Appears to protect against disease
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