Episode two of the IBD chapter takes Crohn disease from phenotype through complete medical management. It runs the Montreal classification into risk stratification and the top-down versus step-up decision, then walks Crohn-specific induction, immunomodulators, and biologic positioning. It closes with the phenotype-specific algorithms for perianal disease, strictures, and post-operative recurrence. Topics covered Montreal classification and phenotype drift Top-down versus step-up risk stratification Crohn-specific induction and steroids Thiopurines and methotrexate Biologics by mechanism and safety Perianal Crohn algorithm Stricturing disease and bowel preservation Post-operative recurrence and Rutgeerts score Key decisions Budesonide 9 mg is induction for mild-to-moderate ileal or right-colonic disease but fails as maintenance beyond six months and does not treat left-sided colonic disease. The high-risk stacked phenotype (young age, deep ulcers, perianal fistula, steroid requirement, smoking) starts biologic plus immunomodulator combination, not step-up. TPMT genotype or activity is mandatory before thiopurines, with NUDT15 testing added in Asian, Hispanic, and Native American patients; hepatosplenic T-cell lymphoma clusters in young men on thiopurine plus anti-TNF. Perianal Crohn sequence is non-negotiable: drain the abscess and place setons first, then start biologic; dose-optimized infliximab on an undrained abscess is the wrong move. Post-operative high-risk patients start prophylactic anti-TNF within four weeks; smoking cessation is the single modifiable factor that meaningfully reduces recurrence. Rutgeerts scope at six to twelve months is universal regardless of risk, and the middle grade or higher triggers escalation. In pregnancy the dominant threat is active disease, not medication: continue most drugs, stop methotrexate and JAK inhibitors. For the full chapter with MCQs, tables, and primary-guideline references, visit www.boardpearls.com. Questions or feedback: [email protected]. (00:00) - Introduction and one disease, many faces (01:11) - Montreal classification and natural history (02:37) - Risk stratification and the top-down decision (04:46) - Medical therapy, steroids, and mesalamine (07:03) - Immunomodulators: thiopurines and methotrexate (09:38) - Biologics by mechanism and safety (15:06) - Perianal Crohn algorithm (16:52) - Stricturing disease and post-operative recurrence

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“What did the council decide on item 42?” — answered with the speaker and the moment.

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