Inflammatory Bowel Disease: Key Differences

Which one of the following features is more common in Crohn's disease than ulcerative colitis?
A. Abdominal mass palpable in the right iliac fossa
B. Tenesmus
C. Bloody diarrhoea
D. Faecal incontinence
E. Abdominal pain in the left lower quadrant

Answer:
A. Abdominal mass palpable in the right iliac fossa

Discussion: The two main types of inflammatory bowel disease are Crohn's disease and Ulcerative colitis. They have many similarities in terms of presenting symptoms, investigation findings and management options. There are however some key differences which are highlighted in table below:

Crohn's disease (CD): 

Clinical Features:

• Diarrhoea usually non-bloody 
• Weight loss more prominent 
• Upper gastrointestinal symptoms, 
• Mouth ulcers, 
• Perianal disease 
• Abdominal mass palpable in the right iliac fossa

Extra-intestinal Features:

• Gallstones are more common secondary to reduced bile acid reabsorption 
• Oxalate renal stones

Complications: 

• Obstruction, fistula, 
• Colorectal cancer

Pathology: 

• Lesions may be seen anywhere from the mouth to anus.
• Skip lesions may be present

Histology: Inflammation in all layers from mucosa to serosa 

 increased goblet cells 

 granulomas

Endoscopy: Deep ulcers, skip lesions - 'cobble-stone' appearance

Radiology: Small bowel enema which shows: 

 high sensitivity and specificity for examination of the terminal ileum 

 strictures: 'Kantor's string sign' 

 proximal bowel dilation 

 'rose thorn' ulcers 

 fistulae

Ulcerative Colitis (UC)

Clinical Features:

• Bloody diarrhoea more common 
• Abdominal pain in the left lower quadrant 
• Tenesmus

Extra-intestinal Features:

• Primary sclerosing cholangitis more common

Complications: 

• Risk of colorectal cancer high in UC than CD

Pathology: 

• Inflammation always starts at rectum and never spreads beyond ileocaecal valve 
• Continuous disease

Histology: 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: Widespread ulceration with preservation of adjacent mucosa which has the appearance of polyps ('pseudopolyps')

Radiology: Barium enema which shows: 

 loss of haustrations 

 superficial ulceration, 'pseudopolyps' 

 long standing disease: colon is narrow and short -'drainpipe colon