IBD, in full.

Two current US guidelines govern Crohn's disease and should be read together. ACG 2025 (Lichtenstein et al.) remains the reference for diagnosis, mild-to-moderate disease, perianal, postoperative and abscess management. DIAGNOSIS: fecal calprotectin (>50-100 μg/g) separates inflammatory from noninflammatory disease of the colon. Workup is ileocolonoscopy with biopsies, including uninvolved mucosa, plus small-bowel imaging. CTE and MRE are comparable; prefer MRE in patients <35 y and when serial exams are likely. Intestinal ultrasound is an ungraded adjunct. Do routine CRC surveillance in Crohn's colitis. MILD-TO-MODERATE: recommend against oral mesalamine; sulfasalazine only for symptomatic mild colonic CD; ileal-release budesonide 9 mg for induction in ileocecal disease but not for maintenance. MODERATE-TO-SEVERE (AGA Living Guideline, Scott et al., Gastroenterology 2025;169(7):1397-1448, 16 recommendations: 1 strong, 9 conditional, 6 knowledge gaps; updated quarterly, adult outpatients only): RECOMMEND infliximab, adalimumab, ustekinumab, risankizumab, mirikizumab, guselkumab or upadacitinib over no treatment; SUGGEST certolizumab pegol or vedolizumab over no treatment. Advanced-therapy-naive: suggest higher-efficacy agents (infliximab, adalimumab, vedolizumab, ustekinumab, risankizumab, mirikizumab, guselkumab) over lower-efficacy ones (certolizumab pegol, upadacitinib). Prior advanced-therapy (especially anti-TNF) exposure: suggest higher- or intermediate-efficacy agents (adalimumab, risankizumab, guselkumab, upadacitinib; ustekinumab, mirikizumab) over lower-efficacy ones (vedolizumab, certolizumab pegol). Suggest against thiopurine monotherapy for induction; suggest it for maintenance of remission. Suggest SC/IM methotrexate monotherapy; suggest against oral methotrexate. In thiopurine-naive patients starting infliximab, suggest infliximab + thiopurine over infliximab alone. No recommendation on IFX + MTX, adalimumab + immunomodulator, or non-TNF biologic + immunomodulator. After ≥6 months of steroid-free remission on anti-TNF + immunomodulator, suggest withdrawing the immunomodulator and suggest against withdrawing the anti-TNF. SUGGEST upfront advanced therapy over step-up therapy (corticosteroids and/or immunomodulator first). No recommendation on treating to endoscopic vs symptomatic remission. The ACG 2025 moderate-to-severe recommendations (anti-TNF, IFX + thiopurine combination and IL-12/23/IL-23 agents, each strong/moderate; upadacitinib after anti-TNF exposure; steroids for short-term induction only; TPMT/NUDT15 testing before thiopurines) still stand alongside AGA. ACG perianal (infliximab first; drain abscesses and place setons before escalating), postoperative (endoscopy at 6-12 months; anti-TNF strong, vedolizumab conditional in high-risk patients) and intra-abdominal abscess (>2 cm: antibiotics plus drainage, hold immunosuppression) positions are unchanged. THERAPEUTIC ENDOSCOPY (AGA Clinical Practice Update, CGH 2026; details below come from AGA news coverage, not the full text, and are ungraded advice): get cross-sectional imaging before the procedure. Endoscopic balloon dilation is first-line for short strictures (about ≤4-5 cm) with few risk factors (fistula, prestenotic dilation >5 cm, high CRP, prior anti-TNF). Longer or multiple strictures, or ≥3 risk factors, favor surgery.

Two current US guidelines govern Crohn's disease and should be read together. ACG 2025 (Lichtenstein et al.) remains the reference for diagnosis, mild-to-moderate disease, perianal, postoperative and abscess management. DIAGNOSIS: fecal calprotectin (>50-100 μg/g) separates inflammatory from noninflammatory disease of the colon. Workup is ileocolonoscopy with biopsies, including uninvolved mucosa, plus small-bowel imaging. CTE and MRE are comparable; prefer MRE in patients <35 y and when serial exams are likely. Intestinal ultrasound is an ungraded adjunct. Do routine CRC surveillance in Crohn's colitis. MILD-TO-MODERATE: recommend against oral mesalamine; sulfasalazine only for symptomatic mild colonic CD; ileal-release budesonide 9 mg for induction in ileocecal disease but not for maintenance. MODERATE-TO-SEVERE (AGA Living Guideline, Scott et al., Gastroenterology 2025;169(7):1397-1448, 16 recommendations: 1 strong, 9 conditional, 6 knowledge gaps; updated quarterly, adult outpatients only): RECOMMEND infliximab, adalimumab, ustekinumab, risankizumab, mirikizumab, guselkumab or upadacitinib over no treatment; SUGGEST certolizumab pegol or vedolizumab over no treatment. Advanced-therapy-naive: suggest higher-efficacy agents (infliximab, adalimumab, vedolizumab, ustekinumab, risankizumab, mirikizumab, guselkumab) over lower-efficacy ones (certolizumab pegol, upadacitinib). Prior advanced-therapy (especially anti-TNF) exposure: suggest higher- or intermediate-efficacy agents (adalimumab, risankizumab, guselkumab, upadacitinib; ustekinumab, mirikizumab) over lower-efficacy ones (vedolizumab, certolizumab pegol). Suggest against thiopurine monotherapy for induction; suggest it for maintenance of remission. Suggest SC/IM methotrexate monotherapy; suggest against oral methotrexate. In thiopurine-naive patients starting infliximab, suggest infliximab + thiopurine over infliximab alone. No recommendation on IFX + MTX, adalimumab + immunomodulator, or non-TNF biologic + immunomodulator. After ≥6 months of steroid-free remission on anti-TNF + immunomodulator, suggest withdrawing the immunomodulator and suggest against withdrawing the anti-TNF. SUGGEST upfront advanced therapy over step-up therapy (corticosteroids and/or immunomodulator first). No recommendation on treating to endoscopic vs symptomatic remission. The ACG 2025 moderate-to-severe recommendations (anti-TNF, IFX + thiopurine combination and IL-12/23/IL-23 agents, each strong/moderate; upadacitinib after anti-TNF exposure; steroids for short-term induction only; TPMT/NUDT15 testing before thiopurines) still stand alongside AGA. ACG perianal (infliximab first; drain abscesses and place setons before escalating), postoperative (endoscopy at 6-12 months; anti-TNF strong, vedolizumab conditional in high-risk patients) and intra-abdominal abscess (>2 cm: antibiotics plus drainage, hold immunosuppression) positions are unchanged. THERAPEUTIC ENDOSCOPY (AGA Clinical Practice Update, CGH 2026; details below come from AGA news coverage, not the full text, and are ungraded advice): get cross-sectional imaging before the procedure. Endoscopic balloon dilation is first-line for short strictures (about ≤4-5 cm) with few risk factors (fistula, prestenotic dilation >5 cm, high CRP, prior anti-TNF). Longer or multiple strictures, or ≥3 risk factors, favor surgery.

Outpatient positioning is unchanged from the ACG 2025 UC guideline and the AGA living guideline for moderate-to-severe UC. Confirm UC with endoscopy showing continuous colonic inflammation from the rectum plus histology, after excluding infection with two-step C. difficile testing. Treat mild-moderate disease with 5-ASA chosen by route and extent: suppository for proctitis, enema for left-sided disease, oral plus rectal for extensive disease. If 5-ASA fails, treat as moderate-to-severe rather than stepping up gradually. Position advanced therapy by efficacy tier, not by an anti-TNF-first rule. Advanced-therapy-naive, higher efficacy: infliximab, vedolizumab, ozanimod, etrasimod, upadacitinib, risankizumab, guselkumab. Intermediate: golimumab, ustekinumab, tofacitinib, filgotinib, mirikizumab. Lower: adalimumab. Previously TNF-exposed, higher efficacy: tofacitinib, upadacitinib, ustekinumab. Lower: adalimumab, vedolizumab, ozanimod, etrasimod. After anti-TNF primary non-response, switch mechanism rather than cycling within the class. Treat to target (STRIDE-II): endoscopic improvement, Mayo endoscopic subscore 0-1. Begin CRC surveillance 8-10 years after diagnosis for extensive or left-sided disease; isolated proctitis follows average-risk screening. Inpatient care now follows the 2026 AGA Clinical Practice Update (13 best-practice statements). Admit for severe symptoms refractory to outpatient therapy, suspected complications (obstruction, abscess, toxic megacolon) or significant malnutrition, and identify acute severe UC by Truelove-Witts. Give every patient admitted with diarrhea two-step C. difficile testing. Test for CMV, with early endoscopy, if symptoms worsen, the patient is systemically toxic or disease is steroid-refractory. Give routine VTE prophylaxis with LMWH or fondaparinux unless contraindicated, and individualize post-discharge extension. Give IV methylprednisolone 60 mg/day or equivalent; the AGA living guideline says 40-60 mg/day, and higher doses add no benefit. Do not give adjunctive antibiotics without infection. Involve surgery early. Assess response by day 3 (72 h) using stool frequency and CRP (Oxford criteria); do not continue IV steroids beyond about 7 days without response. Rescue steroid non-responders with infliximab (accelerated or intensified dosing in selected patients with high inflammatory burden or protein-losing colopathy), cyclosporine, or a JAK inhibitor at standard or intensified dosing, or with colectomy. Before discharge, the response should be stable and a transition plan should be in place.