Inflammatory Bowel Disease
Core concepts
Separate ulcerative colitis (continuous, mucosal, rectal involvement, no skip lesions) from Crohn disease (transmural, skip lesions, perianal disease, fistula). Extraintestinal manifestations include arthritis, erythema nodosum, pyoderma gangrenosum, uveitis, and primary sclerosing cholangitis, which is strongly associated with ulcerative colitis.
Know disease activity assessment: clinical scores, inflammatory markers, fecal calprotectin, and endoscopic healing as the treatment target. Treatment is stepwise by severity and risk: aminosalicylates for mild UC, corticosteroids for induction only (not maintenance), immunomodulators, biologics, and surgery. Recognize acute severe colitis as a medical emergency requiring hospitalization, IV steroids, and early surgical consultation; toxic megacolon and perforation are feared complications.
Traps
Corticosteroids are for induction, not maintenance. Another trap is attributing perianal fistulizing disease to UC. Also watch for questions where a patient on a biologic develops symptoms suggesting infection rather than flare; screen for tuberculosis before starting anti-TNF therapy. Colorectal cancer surveillance begins earlier and is more frequent in long-standing colitis.
Rule of thumb
Treat to endoscopic healing, not just symptom resolution, and never use steroids as long-term maintenance.
Worked example
A patient with severe UC and more than eight stools per day with systemic toxicity needs admission, IV corticosteroids, and surgical consultation; delay risks toxic megacolon.