Acute severe IBD flare in an adult
Admit to hospital. This pathway is for acute severe ulcerative colitis (UC).
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Acute Severe Ulcerative Colitis Management (Adult, ACG 2025)
Acute Severe Ulcerative Colitis Management (Adult, ACG 2025): Acute severe IBD flare in an adult → Crohn's disease (not ulcerative colitis)? → Crohn's d...
Pathway Overview
22 steps
Algorithm Steps
22 total
01Start 02Decision Crohn's disease (not ulcerative colitis)?
Crohn's flares need a different plan: abscess first.
- If Yes
03Warning Crohn's disease: exclude abscess before steroids
Joint gastroenterology and colorectal surgical review. The UC steps below do not apply.
- CT or MRI now for abscess, perforation or obstruction
- Abscess: IV antibiotics and radiological drainage where possible; avoid immediate resection
- No complication: systemic corticosteroids; IBD specialist plans biologic therapy
04End Crohn's flare: continue under the IBD and surgical teams
Use a Crohn's disease pathway for further steps.
If No05Action Ulcerative colitis: confirm acute severe colitis (Truelove and Witts)
6 or more bloody stools/day plus at least 1 sign of systemic toxicity. Criteria not met: not acute severe UC; this pathway does not apply (IBD team plan).
- Pulse >90/min
- Temperature >37.8°C
- Hb <105 g/L
- ESR >30 mm/h or CRP >30 mg/L
06Warning Check first: child, pregnancy, drugs that dilate the colon
Start IV steroids now. Do not wait for stool results.
- Child or adolescent (PUCAI 65 or more): use a paediatric pathway. Doses here are for adults.
- Pregnant: same treatment; uncontrolled colitis harms the pregnancy. Involve obstetric and IBD teams early.
- Stop opioids (including loperamide), anticholinergics and NSAIDs: risk of toxic dilatation
07Action Admission tests (do not delay steroids)
Joint care by gastroenterology and colorectal surgery from admission.
- Stool C. difficile test and culture
- FBC, UEC, LFT, CRP, albumin, Mg, cholesterol
- Abdominal X-ray for colonic dilatation; CT if perforation is suspected
- Flexible sigmoidoscopy with minimal air within 72 h (ideally 24 h): biopsies for CMV
- Send now in case rescue is needed: TB (IGRA and chest X-ray), HBV, HCV, HIV and VZV serology
08Decision Toxic megacolon, perforation or massive bleeding?
Toxic megacolon: colon >6 cm with systemic toxicity. Ask this again every day.
- If Yes
09Warning Surgical emergency: urgent colorectal review for emergency colectomy
Resuscitate. Do not delay surgery.
- Toxic megacolon: colon >6 cm with fever, tachycardia or other signs of toxicity
- Perforation or peritonitis
- Massive or refractory haemorrhage
10End Surgical emergency or failed rescue: subtotal colectomy with end ileostomy
Leave the rectum. Do not delay because of recent infliximab or ciclosporin; delayed surgery worsens outcomes. Restorative surgery (IPAA) can be discussed later.
If No11Action No surgical emergency: IV corticosteroids (adult)
Start at once. Diabetes: check glucose often. Renal impairment: adjust the LMWH dose.
- Methylprednisolone 60 mg IV daily, or hydrocortisone 100 mg IV 6-hourly
- LMWH VTE prophylaxis; rectal bleeding is not a reason to withhold it
- Encourage oral or enteral nutrition; no bowel rest or TPN
- No routine antibiotics
- IV fluids; correct potassium and magnesium; transfuse for significant anaemia
12Warning C. difficile or CMV found: treat it and continue IV steroids
Do not delay rescue therapy or colectomy for the infection.
- C. difficile (adult): oral vancomycin 125 mg 4 times daily or fidaxomicin 200 mg twice daily, for 10 days
- Fulminant C. difficile (shock, ileus or megacolon): vancomycin 500 mg orally 4 times daily plus metronidazole 500 mg IV 8-hourly; rectal vancomycin if ileus; urgent surgical and ID review
- CMV colitis on biopsy with steroid-refractory disease: IV ganciclovir with infectious diseases advice
13Action Every day: stool chart, examination and CRP
Joint review with the colorectal team.
- Stool number, consistency and blood
- Vital signs; abdominal distension or tenderness
- CRP every day
- Repeat abdominal X-ray only if dilatation is suspected
14Decision Day 3 of IV steroids: >8 stools/day, or 3-8 stools/day with CRP >45 mg/L?
Oxford criteria. Yes predicts colectomy in about 85%.
- If Yes
15Warning Steroid-refractory: colorectal review and check before rescue
Start rescue therapy or plan colectomy now. Do not continue IV steroids alone.
- Before infliximab: TB and HBV results; no active sepsis, severe heart failure or demyelinating disease; no past infliximab failure
- Before ciclosporin: normal cholesterol, Mg and creatinine; controlled BP; no uncontrolled infection
- Discuss colectomy as an option with the patient now
16Action Steroid-refractory: rescue with infliximab or ciclosporin (adult)
Choose by team experience, previous therapy and albumin.
- Infliximab 5 mg/kg IV (actual body weight). Albumin <25 g/L: consider 10 mg/kg first dose (IBD specialist)
- OR ciclosporin 2 mg/kg/day by continuous IV infusion over 24 h, then adjust to trough 150-250 ng/mL; monitor BP, creatinine, K and Mg
- Past thiopurine failure, low cholesterol or low Mg: prefer infliximab. Past infliximab or anti-TNF failure: prefer ciclosporin (experienced team) or colectomy
- Not for routine rescue: vedolizumab, adalimumab, tofacitinib, upadacitinib
- Ciclosporin only where the team is experienced with it (off-label in Australia)
- Infliximab with poor response at 3-5 days: accelerated dosing only after colorectal review
- On 3 immunosuppressants: discuss PJP prophylaxis with the IBD team
17Decision Clear response to rescue therapy within 7 days?
No response, deterioration or a complication: colectomy now. Do not wait 7 days.
- If Yes
18Outcome Rescue response: maintenance therapy
After infliximab: complete induction (5 mg/kg at weeks 0, 2 and 6), then maintenance every 8 weeks. After ciclosporin: oral ciclosporin (twice the IV daily dose, in 2 doses; trough 100-200 ng/mL) as a bridge to a thiopurine, or vedolizumab.
If No- Path rejoins step 10Shared downstream outcome
If No19Action Day 3 criteria not met: continue IV steroids and review every day
Response usually shows by day 3-5. Do not continue IV steroids beyond 7 days without rescue therapy.
20Decision Clear response to IV steroids by day 5-7?
No: treat as steroid-refractory (rescue or colectomy).
- If Yes
21Action Clear response: change to oral prednisolone (adult)
- Prednisolone 40 mg orally daily, then taper over 6-8 weeks
- Start maintenance therapy on IBD specialist advice
- Continue VTE prophylaxis while in hospital
22Outcome Remission: maintenance plan and early IBD clinic review
Discharge when stable on oral steroids with a steroid taper and maintenance plan.
If No- Path rejoins step 15Shared downstream outcome
Guideline Source
ACG Clinical Guideline Update: Ulcerative Colitis in Adults (Rubin et al, Am J Gastroenterol 2025;120:1187-1224)
Clinical Safety Information
Clinical Decision Support — Not a Substitute for Clinical Judgment
Individual patient factors may require deviation from these recommendations.
Known Limitations
- Adults with acute severe ulcerative colitis only. Crohn's disease and children need other pathways.
- Rescue choice, accelerated infliximab and a second rescue drug need IBD specialist and colorectal surgical input.
- Tofacitinib and upadacitinib in ASUC: data insufficient for routine use.
- Not yet signed off by a clinical reviewer.
Contraindicated Populations
children and adolescents (use a paediatric ASUC pathway)Crohn's disease flares (abscess must be excluded; use a Crohn's pathway)
Applicable Regions
AUUSEUUKGlobal
AU: Hb and albumin in g/L. Infliximab is PBS-listed for UC (GESA 2024 script guide). Ciclosporin is TGA-registered but UC is not a registered indication (off-label).
EU: ECCO 2022 UC guidelines (medical and surgical treatment).
UK: BSG 2025 IBD guideline (Moran et al, Gut 2025), acute severe UC section.
US: ACG 2025 UC guideline; ASCRS 2026 UC surgery guideline.
Version 2Next review: 2027-09-30
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Frequently Asked Questions
What is the Acute Severe Ulcerative Colitis Management (Adult, ACG 2025)?
The Acute Severe Ulcerative Colitis Management (Adult, ACG 2025) is a emergency clinical algorithm for Gastroenterology. It provides a structured decision tree to guide clinical decision-making, based on ACG Clinical Guideline Update: Ulcerative Colitis in Adults (Rubin et al, Am J Gastroenterol 2025;120:1187-1224).
What guideline is the Acute Severe Ulcerative Colitis Management (Adult, ACG 2025) based on?
This algorithm is based on ACG Clinical Guideline Update: Ulcerative Colitis in Adults (Rubin et al, Am J Gastroenterol 2025;120:1187-1224) (DOI: 10.14309/ajg.0000000000003463).
What are the limitations of the Acute Severe Ulcerative Colitis Management (Adult, ACG 2025)?
Known limitations include: Adults with acute severe ulcerative colitis only. Crohn's disease and children need other pathways.; Rescue choice, accelerated infliximab and a second rescue drug need IBD specialist and colorectal surgical input.; Tofacitinib and upadacitinib in ASUC: data insufficient for routine use.; Not yet signed off by a clinical reviewer.. Individual patient factors may require deviation from these recommendations.
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