comparison of ulcerative colitis with Crohn's disease

Last reviewed 05/2022

Clinically, bloody diarrhoea is seen in nearly all patients with ulcerative colitis, but only half of those with Crohn's. An abdominal mass is common in Crohn's but rare in UC; perianal disease is common in Crohn's, but again rare in UC. There is never rectal sparing in UC.

Histologically, UC is a mucosal disease with distorted glands and no granulomata; Crohn's is transmural with normal glands and granulomata.

Radiologically, UC is a symmetrical, continuous disease causing shallow ulcers but very rarely strictures and never any fistulae. Crohn's is discontinuous with deep ulcers with common strictures and fistulae.

This said, a firm diagnosis is not made in 15-20% of patients.