Ulcerative Colitis

See Inflammatory Bowel Disease for shared epidemiology, classification, clinical features, and diagnosis. This page covers UC-specific medical management, acute severe UC, and surgical indications/options. The medical-management and ASUC sections below are sourced from a 2025 ACG society guideline (ACG 2025 - Ulcerative Colitis Guideline) — GRADE-based recommendations plus expert-consensus statements, one tier more authoritative than a single trial but not independently re-verified against each underlying trial. The surgical-options section remains sourced from the textbook reference chapter (Sabiston Ch52 - Inflammatory Bowel Disease).

Disease severity and monitoring

Beyond the extent-based classification on Inflammatory Bowel Disease (proctitis/left-sided/ extensive), the ACG guideline layers in a severity framework: the ACG UC Disease Activity Index combines patient-reported outcomes (stool frequency, bleeding, urgency), labs (hemoglobin, ESR, CRP, fecal calprotectin), and endoscopy (Mayo endoscopic subscore or UCEIS) into remission/mild/moderate-severe/fulminant tiers — more multidimensional than the Truelove and Witts criteria referenced on Inflammatory Bowel Disease.

Treatment goal is endoscopic improvement (Mayo endoscopic subscore 0–1), not symptomatic remission alone — endoscopically healed mucosa correlates with sustained steroid-free remission and lower colectomy risk. "Deep remission" = symptomatic remission + endoscopic healing. Fecal calprotectin is a validated tool for both diagnosis and ongoing monitoring (response to therapy, suspected relapse, maintenance surveillance). Intestinal ultrasound is a newly endorsed point-of-care monitoring adjunct (pooled sensitivity 85%, specificity 92% vs. endoscopy/biomarkers), though US credentialing pathways are still maturing.

Mayo endoscopic subscore detail (Table 44.7, ASCRS Ch44): 0 normal/inactive, 1 mild (erythema, decreased vascular pattern, mild friability), 2 moderate (marked erythema, absent vascular pattern, friability, erosions), 3 severe (spontaneous bleeding, ulceration) — 0–1 is the treat-to-target threshold referenced above. The Modified Mayo Endoscopic Score (MMES) refines this further; see Inflammatory Bowel Disease's "Endoscopic and clinical activity scoring systems" section for the full scoring suite (including UC's overall Mayo score 0–12 and the Crohn's-specific scores). Extent/severity classification detail: Montreal E1–E3 (extent: proctitis/left-sided/ extensive) and S0–S3 (severity), plus the pediatric Paris classification's PUCAI activity index, are detailed on Inflammatory Bowel Disease's "Classification" section rather than duplicated here.

Truelove and Witts criteria (Table 45.1, ASCRS Ch45) — the older of the two severity systems referenced above, still commonly used to define ASUC: rates six variables (defecation frequency, bloody stool, fever, tachycardia, anemia, ESR) as mild/moderate/severe. "Mild" requires all six criteria at the mild threshold (≤4 stools/day, no/trace blood, no fever, no tachycardia, no anemia, normal ESR); "severe" requires ≥6 stools/day plus bloody stool, and either a systemic-toxicity criterion (fever ≥37.5°C or tachycardia ≥90/min) plus at least 4 of the 6 criteria overall met at the severe threshold. Mayo score system (Table 45.2) grades four domains 0–3 each (stool frequency, rectal bleeding, endoscopic findings, physician's global assessment) for a combined 0–12 score — the "Mayo score" referenced throughout the pivotal-trial data in "Medical management" below.

Medical management

Stepwise, extent- and severity-guided. See Inflammatory Bowel Disease for the shared drug-class table (mechanism, route); this section adds UC-specific dosing, sequencing, and trial evidence.

Mildly to moderately active UC:

• Topical (rectal) 5-ASA preferred first-line for proctitis/left-sided disease over topical corticosteroids. Oral 5-ASA ≥2.0 g/d for extensive colitis. Combination oral + rectal 5-ASA outperforms oral alone for left-sided disease. No benefit to dose-escalating 5-ASA beyond ~2.4 g/d in low-activity disease. Mechanism (ASCRS Ch45): 5-ASA activates PPAR-γ nuclear receptors controlling apoptosis/cell proliferation/inflammation/metabolic function, most highly expressed in colon epithelial cells; formulations differ in how they achieve colonic delivery (bacterial-, pH-, and time-mediated release). Sulfasalazine vs. mesalamine side-effect profile: sulfasalazine (5-ASA bound to a sulfapyridine moiety, cleaved by colonic bacteria) carries a wider range of serious adverse events via the sulfapyridine component — GI upset, headache, bone marrow suppression, fever, hemolytic anemia, hepatitis, hypersensitivity, pancreatitis, pneumonitis, rash — and requires concomitant folic acid (1 mg/day) since it depletes folate stores; mesalamine's profile is cleaner (rare interstitial nephritis; routine renal-function monitoring recommended).
• Budesonide MMX 9 mg/d for 5-ASA nonresponders or 5-ASA-intolerant patients. Three budesonide formulations exist: two standard capsules release in the terminal ileum/right colon, while budesonide MMX® releases throughout the entire colon — chosen for its extensive first-pass hepatic metabolism, which maximizes local availability while minimizing systemic glucocorticoid effects. A dose-finding RCT found induction remission rates of 17.9%/13.2%/12.1%/7.4% for budesonide MMX 9mg/budesonide MMX 6mg/5-ASA/placebo respectively, with statistical significance only at the higher budesonide dose.
• Oral corticosteroids if 5-ASA fails outright, or for any extent of UC not responding to 5-ASA.
• Probiotics and fecal microbiota transplant: insufficient evidence to recommend as primary induction therapy at this time. Curcumin (ASCRS Ch45) — genuinely new to the wiki: the turmeric-derived pigment, postulated to work via NF-κB suppression and Th1/Th2 cytokine modulation, showed a threefold increase in clinical/endoscopic response as an adjunct to mesalamine in a meta-analysis of 7 studies/380 patients (21 mostly-mild adverse events); not FDA-approved for UC. A separate meta-analysis suggests bifidobacteria-containing probiotics show promise for active disease specifically, though probiotics remain unapproved for any IBD indication.

Moderately to severely active UC — advanced therapy roster (this is genuinely new to the wiki; previously only the bare drug-class table on Inflammatory Bowel Disease existed with no UC-specific positioning or trial evidence):

Pivotal trial dosing and response rates (Tables 45.4–45.5, ASCRS Ch45 — concrete numbers behind the qualitative positioning above):

Side-effect rates (serious infections, malignancy) were broadly similar between treatment and placebo arms across all six pivotal programs, with tofacitinib the exception (increased herpes zoster and overall infection risk, most pronounced at the 10mg maintenance dose — the basis for preferring the 5mg maintenance dose where feasible).

No head-to-head trials exist between most of these classes; the ACG guideline explicitly declines to use network meta-analysis/indirect comparisons to rank them, except where real RCT data exists (vedolizumab vs. adalimumab, above). Agent choice in practice is guided by prior anti-TNF exposure, infection risk, extraintestinal manifestations (choose an agent effective at both gut and joint/skin sites), and avoiding payer-driven step therapy. On secondary loss of anti-TNF response, reactive therapeutic drug monitoring (trough levels + antidrug antibodies) is recommended; routine proactive TDM in all patients is not yet evidence-supported.

Efficacy positioning — a genuine disagreement between guidelines

ACG 2025 - Ulcerative Colitis Guideline (above) explicitly declines to rank therapies by network meta-analysis (NMA). AGA 2024 - Moderate-to-Severe UC Pharmacotherapy Guideline does the opposite — it builds an explicit "higher/intermediate/lower efficacy" bucket system substantially from NMA p-scores, on the reasoning that with 11+ approved agents and few head-to-head trials, some positioning guidance beats none. Both approaches are legitimate GRADE-consistent choices, not an error in either guideline, but they are not simply additive — treat the two guidelines' positioning tables as reflecting different evidentiary philosophies, not different snapshots of the same ranking. The AGA buckets:

Note vedolizumab moves from the higher bucket (naive) to the lower bucket (biologic-exposed) — these are population-specific buckets, not a fixed drug ranking. Both guidelines agree on the one real head-to-head data point (VARSITY: vedolizumab > adalimumab) and both treat infliximab and upadacitinib favorably; the AGA's added granularity is the population-specific bucket-flipping the ACG guideline deliberately avoided producing.

Combination therapy, de-escalation, and sequencing (AGA 2024)

• Infliximab + immunomodulator (thiopurine) is recommended over either agent alone — direct trial evidence from the UC-SUCCESS trial: corticosteroid-free remission 39.7% (combination) vs. 22.1% (infliximab alone) vs. 23.7% (azathioprine alone) at week 16; mucosal healing 62.8% vs. 54.6% vs. 36.8%. Adalimumab or golimumab + immunomodulator is also recommended over monotherapy, though this is extrapolated from TNF-class mechanism similarity and Crohn's-trial evidence (SONIC) rather than a UC-specific RCT for those two agents. No recommendation (knowledge gap) for combining immunomodulators with non-TNF biologics — no clear benefit shown, unlike the TNF class. Trade-off: combination therapy carries higher lymphoma risk than TNF-antagonist monotherapy (HR 2.53) or thiopurine monotherapy (HR 2.35) in observational French national data, without a matching serious-infection increase.
• De-escalation (a topic the ACG 2025 guideline does not address at all): suggests against withdrawing the TNF antagonist after ≥6 months of corticosteroid-free remission on TNF + immunomodulator combination therapy — withdrawal roughly doubles relapse risk at 12 months (31.5% vs. 11.2%). No recommendation on withdrawing the immunomodulator instead while continuing the biologic (knowledge gap; underlying trial data mostly drawn from Crohn's populations).
• 5-ASA discontinuation on escalation: once a patient has escalated to immunomodulators/advanced therapy after 5-ASA failure, suggests stopping 5-ASA (no treatment-effect modification found in a pooled 10-RCT, 6044-patient analysis) — except patients with residual proctitis, who may still benefit from adding rectal 5-ASA.
• Step therapy: suggests early use of advanced therapy over gradual step-up once a patient meets moderate-to-severe criteria — with an explicit shared-decision caveat that patients who weight 5-ASA's safety profile highly may reasonably choose gradual step therapy instead.
• Pregnancy (also outside ACG 2025's scope): avoid JAK inhibitors and S1P receptor modulators in women of childbearing age contemplating pregnancy (limited safety data); TNF antagonists/other biologics have reassuring large-registry (PIANO) data.

Acute severe UC (ASUC)

Defined as ≥6 bowel movements/day plus ≥1 systemic toxicity sign (tachycardia, fever, hemoglobin <10.5 g/dL, or elevated inflammatory markers/CRP). Management algorithm (ACG 2025 Fig. 3):

• Day 0: baseline stool studies including C. difficile; flexible sigmoidoscopy within 72h (preferably 24h) for severity assessment and CMV biopsy; assess for toxic megacolon; VTE prophylaxis; hold 5-ASA (risk of paradoxical diarrhea). Treat CDI (fidaxomicin or vancomycin) or CMV (ganciclovir/valacyclovir) if positive — without withholding UC-directed therapy. If both negative: start IV corticosteroids without delay (methylprednisolone ≤60 mg/d or hydrocortisone 100 mg 3–4×/day).
• Day 3: reassess. Responding (<4 BM/day for 2 days, no bleeding) → transition to oral prednisone 40 mg, manage as outpatient. Not responding → escalate to IV cyclosporine (2–4 mg/kg, target trough 150–250 ng/mL) or infliximab (5 mg/kg, or 10 mg/kg if low albumin) or (emerging, off-label, explicitly flagged as under investigation rather than a formal recommendation) tofacitinib/upadacitinib. Cyclosporine dosing detail (ASCRS Ch45): an RCT comparing 2 mg/kg/day to 4 mg/kg/day found similar clinical response and colectomy rates between the two, making 2 mg/kg/day the recommended ASUC dose — the lower end of the range above.
• Day 6: reassess again. Response → maintain on whichever rescue agent worked. No response, or development of toxic megacolon/perforation/severe refractory hemorrhage → surgery.
• Choice between infliximab and cyclosporine rescue is based on provider/institutional familiarity, prior immunomodulator/anti-TNF exposure, and serum albumin — thiopurine-naive patients starting cyclosporine have lower subsequent colectomy risk than thiopurine-exposed/-failed patients. A 115-patient RCT directly comparing the two found similar treatment-failure rates in the short term and similar 1- and 5-year colectomy-free survival; the separate CONSTRUCT trial (ASCRS Ch45) compared quality of life and healthcare costs between the two agents and likewise found no difference in quality-adjusted survival, colectomy frequency/timing, or adverse events including mortality. Sequential salvage (infliximab after cyclosporine failure or vice versa) carries a significant colectomy rate (up to 60% at 1 year in some series) and is not generally recommended. Limited data on the CT-P13 infliximab biosimilar in ASUC rescue therapy (two small cohorts, 63 and 83 patients) show comparable efficacy, mucosal healing, and colectomy-free survival to originator infliximab.
• Important correction to older surgical teaching: neither infliximab nor cyclosporine rescue therapy increases postoperative complications of colectomy, and necessary surgery should not be delayed for a biologic "washout" period out of concern for this. Delayed surgery is independently associated with worse postoperative outcomes — early surgical consultation/referral is recommended proactively, not reserved as a last resort.
• Nutrition: enteral feeding preferred over bowel rest/TPN (no RCT benefit shown for bowel rest). Malnutrition (weight loss >10–15%/6mo, BMI <18.5, albumin <30 g/L) should be corrected before colectomy where feasible.
• Preferred surgery for ASUC remains subtotal/total colectomy with end ileostomy (not one-stage restorative proctocolectomy) — matches the surgical-options section below; pouch construction is deliberately deferred to a later, better-optimized stage.

Maintenance of remission (ASCRS Ch45)

A dedicated maintenance framework — genuinely new structure for the wiki; prior content covered induction/advanced-therapy positioning but not systematically addressed who needs ongoing therapy or how each drug class performs specifically for maintenance.

• Who doesn't need it: patients with isolated ulcerative proctitis, less than one flare per year, and response to topical mesalamine typically enjoy long-term remission without relapse and don't require ongoing maintenance therapy. Patients with proctosigmoiditis, or colitis extending proximal to the sigmoid (left-sided/extensive), more often require maintenance.
• 5-ASA: not recommended for maintenance after achieving remission with immunomodulators, biologics, or tofacitinib (no benefit shown in that setting). For patients who achieved remission on topical 5-ASA alone with mildly active proctitis, rectal 5-ASA (1 g/day) maintenance is reasonable (7-trial meta-analysis shows improved remission vs. placebo). For mildly active left-sided/extensive disease, oral 5-ASA (≥2 g/day) maintenance is supported by an 11-trial meta-analysis; standard-to-high dose outperforms low-dose, but formulation itself doesn't predict relapse risk.
• Budesonide MMX® has not been studied for maintenance of either mild-to-moderate or moderate-to-severe disease.
• Glucocorticoids (systemic): explicitly not recommended for maintenance given their side-effect profile — taper over 8–12 weeks instead of continuing.
• Thiopurines: effective for maintenance (4 placebo-controlled trials plus 3 trials comparing thiopurines to 5-ASA-containing compounds; also effective in patients who failed or couldn't tolerate sulfasalazine/mesalamine) — ACG and AGA both recommend thiopurines for maintenance.
• Methotrexate NOT recommended for maintenance — two separate RCTs found no superiority over placebo, including the US-based MERIT-UC trial (66% relapse on methotrexate vs. 63% on placebo). AGA does not recommend methotrexate monotherapy for this purpose.
• Tofacitinib: 52-week maintenance remission rates of 34.3%/40.6%/11.1% at 5mg BID/10mg BID/ placebo respectively — no increased VTE at either dose in the maintenance trial, but increased herpes zoster risk at the 10mg dose (part of the rationale for preferring 5mg maintenance where clinically feasible, consistent with the advanced-therapy roster's JAK-inhibitor note above).
• Biologics: anti-TNF agents (infliximab, adalimumab, golimumab) all superior to placebo for maintenance per a 6-RCT systematic review/meta-analysis, with no single agent shown superior to another. Vedolizumab similarly superior to placebo (4-study, 606-patient systematic review); in induction-responders, 40% maintained remission at week 52 on vedolizumab vs. 16% on placebo. Ustekinumab maintenance data show a similar pattern (dose-dependent remission 38.4–43.8% vs. 24% placebo at week 44).
• Biosimilar switching: a study of patients switched from infliximab to the CT-P13 biosimilar found no changes in 6-month disease-activity scores, CRP, hemoglobin, fecal calprotectin, or drug- antibody levels; an 8-study/594-patient meta-analysis found switching to be an effective and cost-effective strategy; a separate multicenter observational cohort confirmed sustained mucosal healing at week 54 post-switch.

Indications for surgery

Elective/emergent split and ASUC colectomy risk-scoring (ASCRS Ch49): approximately 30% of UC patients undergo surgery in their lifetime; most is elective (medically refractory colitis makes up ~70% of the surgical cohort), but 10% require emergent surgery. Notably, a survey of UC patients having surgery found over 50% felt they should have had surgery at an earlier time-point — supporting early surgical evaluation rather than exhausting every medical option first. For ASUC specifically, a 270-patient study (2002-2017) found prior thiopurine/anti-TNF treatment (HR 3.86), C. difficile infection (HR 3.73), CRP >30mg/L (HR 3.06), and albumin <3.0g/dL (HR 2.67) independently predicted colectomy; a simple risk score (1 point per factor) found cumulative 1-year colectomy risk of 0%, 9%, 11%, 51%, and 100% for scores of 0 through 4. Despite this, surgical thresholds remain high — delaying until all medical options are exhausted raises surgical morbidity (>50%) and in-hospital mortality (8%); the chapter authors advocate framing surgery as an alternative to medical management in hospitalized ASUC, not a last resort. Full chapter summary: ASCRS Ch49 - Ulcerative Colitis Surgical Management.

• Failure to respond to maximal medical therapy — the most common indication. Ranges from patients with poor quality of life (urgency, tenesmus, poor nutritional status, "failure to thrive") to more acute failure.
• Fulminant colitis — hospitalized, on IV steroids, sometimes in-hospital biologics or IV cyclosporine as an attempt to avoid colectomy (see "Acute severe UC (ASUC)" above for the current ACG-guideline-based escalation algorithm and timing). Toxic megacolon may be present: defined as 3 or more of {tachycardia >100, leukocytosis >12,000/dL, hypoalbuminemia <3 g/dL, temperature

  38°C} plus transverse colon diameter >5 cm on plain film. Note: a "megacolon" alone (dilation without toxicity) does not meet the definition — both toxicity criteria and dilation are required. Colonic perforation risk is significant when this develops.

• Significant GI hemorrhage — an indication for urgent surgery in a minority of cases; frequency of this indication has decreased over time.
• Failure to grow — indication in children.
• Dysplasia or cancer — colectomy indicated. Patients with longstanding UC (>8 years) are at high risk of dysplasia/cancer, more so with concurrent sclerosing cholangitis. "Flat" dysplasia is harder to detect than "polypoid" dysplasia, which can sometimes be managed with polypectomy and continued surveillance if isolated. Multiple areas of flat dysplasia, or any high-grade dysplasia, is an indication for colectomy. Surveillance schedule and technique: see Inflammatory Bowel Disease's "Colorectal cancer surveillance in IBD" section for the full risk-stratified interval framework (annual/1–3yr/3–5yr by risk tier), chromoendoscopy-vs-standard- definition RCT evidence, the 4-random-biopsies-per-10cm protocol, and SCENIC terminology (which has replaced "DALM") — that content applies to UC as the risk-driving condition in most of its cited evidence. UC-specific CRC epidemiology and SCENIC visible/invisible-dysplasia detail (ASCRS Ch49): overall CRC rate in UC is 3.7%, rising with duration — 2% at 10 years, 8% at 20 years, 18% at 30 years after disease onset (compare Crohn Disease's Ch48-added cumulative-risk figures — 2.9%/ 5.6%/8.3% at the same milestones — consistent with Ch48's own observation that CD's risk appears lower than UC's at equivalent duration, though possibly reflecting distribution differences rather than a true biological gap). SCENIC distinguishes visible/invisible and polypoid/non-polypoid dysplasia: endoscopically resected polypoid dysplasia may be followed with surveillance colonoscopy rather than colectomy; surveillance of non-polypoid (flat) dysplasia remains conditional/ controversial against other guidelines recommending surgical referral; SCENIC has also challenged routine random quadrant biopsies. Historical (low-definition-endoscopy-era) data found CRC in the colectomy specimen in 22% of patients with invisible low-grade dysplasia and 32-42% with invisible high-grade dysplasia — rates that justified colectomy even for low-grade dysplasia at the time — but SCENIC attributes these high historical rates to missed lesions pre-high-definition endoscopy: only 10% of dysplasia-positive biopsies are "invisible" in the current era vs. 87% previously. This genuinely extends, without contradicting, this page's brief "flat vs. polypoid" framing above.
• Severe extraintestinal disease not responding to medical therapy is an indication in some patients, though some extraintestinal manifestations run a course independent of the colon.

Preoperative planning (ASCRS Ch49) — new to this page: enterostomal therapist consultation for ostomy site marking; preoperative small bowel evaluation (if not recently done) to exclude small bowel inflammation/confirm the UC diagnosis; a steroid taper as tolerated. Except for documented adrenal insufficiency, perioperative corticosteroid stress dosing is not recommended and may increase infectious complications — patients with prolonged steroid exposure should instead be maintained on their preoperative dose with a taper on discharge (this UC-specific guidance mirrors the Crohn's-specific perioperative steroid detail ASCRS Ch48 added to Crohn Disease). Preoperative nutritional optimization/prehabilitation may improve recovery, though IBD-surgery- specific data is limited. Oral antibiotics plus mechanical bowel preparation is recommended to minimize postoperative infectious complications.

Surgical options

• Total proctocolectomy with end ileostomy (subtotal colectomy + ileostomy + Hartmann's approach) — treatment for fulminant colitis not responding to maximal medical therapy. A known complication is "blow-out" of the Hartmann stump leading to a pelvic abscess; avoided by leaving a long Hartmann stump incorporated into the fascial closure or extraction site, with the skin left open (a controlled mucous fistula rather than a deep pelvic infection). Restoration of continuity is typically deferred ~3 months, once the patient is stabilized and weaned off immunosuppression.
• Subtotal colectomy with ileorectal anastomosis (IRA) — avoids pelvic dissection entirely (so avoids the sexual dysfunction/fertility risks of pelvic dissection). Best suited to patients with limited rectal involvement, which is uncommon in UC (disease is usually worst distally). Retained rectum requires ongoing dysplasia surveillance. Outcome/risk data (ASCRS Ch49): overall complications 24-28%, anastomotic leak 3-4%; long-term failure rate (the dominant concern) ranges 18-49%. A 343-patient French multicenter retrospective study found preoperative immunosuppressant/anti-TNF treatment predicted IRA failure — the chapter text also describes colectomy-for-severe-acute-colitis as associated with decreased failure risk in one clause after naming it as a failure predictor earlier; this apparent internal inconsistency is preserved here rather than silently resolved, since the wiki could not disambiguate it from the available chapter text. On cancer risk in the retained rectum: an 89-patient study found rectal- remnant cancer rates from 0% (<10yr disease) to 13% (>25yr); patients with cancer/dysplasia in the colon at colectomy had substantially higher subsequent rectal cancer/precancer risk (22% with mild colonic dysplasia, 71% with colon cancer/precancer). A meta-analysis found subsequent CRC risk of 2.1% (rectal stump), 2.4% (IRA), and 0.5% (IPAA) — IRA/rectal-stump risk significantly exceeds IPAA (OR 6.4); prior CRC is the strongest subsequent-CRC risk factor after both IRA (OR 12.8) and IPAA (OR 15.0). Reasonable selective-IRA candidates: ASUC patients naïve to biologics/immunomodulators, indeterminate colitis with rectal sparing, and young women prioritizing fertility preservation — but chronic UC's impact on rectal compliance, and surgeon capability with both operations, are additional considerations. Not independently verified against primary literature.
• Ileal Pouch–Anal Anastomosis (IPAA) — the most popular procedure for UC that fails medical therapy or requires colectomy for dysplasia. See the dedicated procedure page for technique, complications, and functional outcomes — now substantially expanded (ASCRS Ch49) with full operative-technique detail, the one-/two-/three-stage and modified-two-stage staging controversy, pouch-design (J/S/W) outcome comparisons, hand-sewn-vs- stapled trial evidence, and the transanal-pouch (ta-J-pouch) approach.
• Continent ileostomy — historically the option for young UC patients before IPAA existed; largely superseded by IPAA. Continence is maintained by an intussuscepted segment of ileum (rather than the anal sphincter) between the reservoir and the end ileostomy; prone to desussception (the intussuscepted segment reduces spontaneously), which renders the stoma incontinent and requires revisional surgery. Works best in thin patients — heavier mesentery in larger patients predisposes to desussception. Full operative/complication detail (ASCRS Ch49) — genuinely new depth for this page: uses the terminal 45-50cm of ileum (Kock pouch) — distal 3-5cm forms the outlet, next 18cm the intussuscepted nipple valve, proximal 30cm the reservoir. Suspected Crohn's disease contraindicates the procedure (recurrent disease may require resecting the entire ~45cm pouch, risking malnutrition); obesity and age >40 are relative contraindications. Nipple-valve slippage is the most common complication (~30% of patients) and virtually always requires surgical correction once it occurs; wrapping the valve in prosthetic material reduces slippage but raises parastomal abscess/fistula risk. Pouchitis occurs in 25% (second most common complication), intestinal obstruction in ~5%, and fistula (usually from the pouch itself or the nipple-valve base) in ~10% — base-of-valve fistulas cause incontinence and rarely heal without reoperation. Despite frequent complications, ~90% of patients eventually achieve total continence after one or more procedures, and reported satisfaction is high. The Barnett modification (afferent-limb-constructed valve wrapped with residual efferent limb) has no controlled data showing superiority over the standard technique most centers use. Beyond its role as a primary operation, continent ileostomy is also used as a pouch-salvage option for patients with a failed IPAA who want continence but aren't candidates for a redo pelvic pouch (ASCRS Ch50) — see Ileal Pouch-Anal Anastomosis (IPAA)'s "Managing pouch failure" section.

Open items / gaps

• ASCRS Ch49 ("Ulcerative Colitis: Surgical Management") added the elective/emergent surgery split, ASUC colectomy risk-scoring, SCENIC visible/invisible-dysplasia and CRC-epidemiology detail, preoperative planning, full IPAA staging-controversy/pouch-design/anastomosis-type evidence (added primarily to Ileal Pouch-Anal Anastomosis (IPAA)), a fully fleshed-out IRA section with failure-rate and cancer-risk data, and full continent-ileostomy operative/complication detail — see "Indications for surgery" and "Surgical options" above, full chapter summary on ASCRS Ch49 - Ulcerative Colitis Surgical Management. One unresolved internal inconsistency flagged rather than silently fixed: the chapter's IRA-failure-predictor discussion names colectomy- for-severe-acute-colitis as both a failure predictor and (in a separate clause) associated with decreased failure risk — could not be disambiguated from the available chapter text, so both readings are preserved. Every named trial/study (the 270-patient ASUC risk-score study, the 343-patient French IRA study, the 89-patient rectal-remnant-cancer study, the CRC-risk-by-procedure meta-analysis, PUCCINI, and every trial cited on Ileal Pouch-Anal Anastomosis (IPAA)) is textbook/secondary-level only.
• ASCRS Ch45 added a dedicated maintenance-of-remission framework, concrete pivotal-trial dosing/ response tables (Tables 45.4–45.5), curcumin as a genuinely new adjunct-therapy topic, and CONSTRUCT-trial/biosimilar-rescue detail for ASUC — see "Medical management", "Maintenance of remission", and "Acute severe UC" above, full chapter summary on ASCRS Ch45 - Medical Management of Ulcerative Colitis. Heavily overlapping with the existing ACG/AGA-guideline-sourced content otherwise — VARSITY's numbers are now independently cited by three secondary sources (ACG, AGA, this chapter) but still not independently read from the primary trial. Every other named trial in Ch45 (UC-SUCCESS, MERIT-UC, GEMINI, UNIFI, ACT 1/2, ULTRA 1/2, PURSUIT-SC, OCTAVE 1/2, the CT-P13 biosimilar-switch studies) is likewise textbook/secondary-level only.
• ASCRS Ch44 added Mayo endoscopic subscore detail and a risk-stratified CRC surveillance framework (see "Disease severity and monitoring" and "Indications for surgery" above, full detail on Inflammatory Bowel Disease). The chromoendoscopy-vs-standard-definition question noted below is now partially answered: two RCTs cited by Ch44 found no added dysplasia-detection benefit from chromoendoscopy — but this is still textbook/secondary-level citation, not an independent read of either trial.
• No primary trial data yet on IPAA vs. ileorectal anastomosis vs. end ileostomy outcomes.
• ~~Pouchitis — mentioned only via the sclerosing-cholangitis risk link on Inflammatory Bowel Disease; no dedicated coverage yet.~~ Resolved — Ch43 added a full "Pouchitis" section to Ileal Pouch-Anal Anastomosis (IPAA) (incidence, IL-1 SNP/NOD2/TLR2-4/ defensin associations, fecal-stasis metaplasia, microbiome shift).
• Cuffitis (retained-rectal-mucosa inflammation after IPAA) mentioned only briefly on Ileal Pouch-Anal Anastomosis (IPAA) — not developed as its own topic.
• The ACG and AGA guidelines take explicitly different methodological stances on ranking therapies by network meta-analysis (see "Efficacy positioning" subsection above) — treat their positioning tables as reflecting different evidentiary philosophies, not reconcilable into one ranking, except where real head-to-head RCT data exists (vedolizumab vs. adalimumab).
• ASUC section (from ACG 2025 only, not covered by AGA 2024's narrower moderate-severe-outpatient scope) still rests on a single guideline for its day-by-day algorithm, though BSG 2025 - IBD Guidelines (Adults) (ingested alongside ACG/AGA) covers UC broadly too and wasn't exhaustively cross-checked against this page's specific numbers — see that guideline's own Limitations note. BSG's therapeutic-drug-monitoring and pregnancy content (both cross-cutting UC+Crohn's topics) was filed on Inflammatory Bowel Disease instead of duplicated here.