Inflammatory Bowel Disease
Inflammatory bowel disease questions combine classification, activity assessment, infection exclusion and treatment sequencing. The board favors acute severe ulcerative colitis, treat-to-target strategy and biologic safety screening.
Classification and assessment
- Ulcerative colitis is continuous from the rectum; Crohn disease shows skip lesions, transmural inflammation, fistulae and perianal involvement. Use Montreal classification for age, location and behavior.
- Activity: Mayo score for ulcerative colitis; Crohn Disease Activity Index or Harvey-Bradshaw Index for Crohn. Fecal calprotectin distinguishes inflammatory from functional diarrhea but is nonspecific.
- Before starting immunosuppression, exclude C. difficile (testing everyone with a flare), consider CMV in steroid-refractory colitis by colonic biopsy and serum CMV DNA, and check stool culture where indicated.
Treatment targets and sequencing
- STRIDE-II targets: clinical response early, clinical remission and calprotectin normalization, then endoscopic healing.
- Mild to moderate ulcerative colitis: mesalamine, at least 2 g/day, with topical therapy for proctitis. Steroids for induction only, never maintenance.
- Moderate to severe disease: thiopurines, then biologics (anti-TNF, vedolizumab, ustekinumab) or JAK inhibitors.
- Screen for latent tuberculosis (interferon-gamma release assay and chest radiograph) and hepatitis B before anti-TNF or JAK therapy, particularly important in high-TB-prevalence settings.
Acute severe ulcerative colitis
- Truelove and Witts criteria: six or more bloody stools daily plus one of fever, tachycardia, anemia or elevated ESR.
- Admit, give IV hydrocortisone, thromboprophylaxis, fluid and electrolyte replacement, and stool testing for C. difficile and CMV.
- Assess response at day 3 (stool frequency above 8 or CRP above 45 predicts colectomy). If failing, start rescue infliximab or cyclosporine; discuss surgery with the patient early.
Surveillance, pregnancy, special situations
- Dysplasia surveillance with chromoendoscopy or high-definition white light from 8 years of disease, every 1-5 years by risk.
- Continue mesalamine, thiopurines and biologics in pregnancy; stop methotrexate at least 3 months before conception.
- Primary sclerosing cholangitis raises colorectal cancer risk and warrants annual colonoscopy.
Worked example
A 28-year-old with ulcerative colitis has 8 bloody stools daily, temperature 38.2 C, hemoglobin 9 g/dL and CRP 60 after 3 days of IV steroids. This is steroid-refractory acute severe colitis: start rescue infliximab, involve colorectal surgery, and repeat stool testing for C. difficile.
Traps
- Using steroids as maintenance.
- Diagnosing Crohn disease from a single biopsy.
- Missing CMV in a steroid-refractory flare.
- Starting anti-TNF without tuberculosis and hepatitis B screening.