Suspected toxic megacolon (adult)
Colonic dilatation with systemic toxicity. Call the colorectal surgical team now. No surgeon on site: arrange urgent transfer.
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Colorectal SurgeryEmergency
Toxic Megacolon Management (ASCRS/ACG)
Toxic Megacolon Management (ASCRS/ACG): Suspected toxic megacolon (adult) → Confirm: Jalan criteria → Immediate care (all patients) → Tests and history:...
Pathway Overview
16 steps
Algorithm Steps
16 total
01Start 02Action Confirm: Jalan criteria
Colon dilated more than 6 cm on imaging, plus signs of toxicity
- Colon diameter more than 6 cm on X-ray or CT
- Plus 3 or more: fever above 38.6 °C, heart rate above 120/min, WCC above 10.5 x10^9/L, anaemia
- Plus 1 or more: dehydration, altered mental state, electrolyte disturbance, hypotension
- Dilatation with severe toxicity is enough to act; do not wait for every criterion
03Action Immediate care (all patients)
Resuscitate in HDU or ICU. Sepsis or peritonitis: IV broad-spectrum antibiotics now (local guideline). Stop drugs that slow the colon.
- IV fluids; correct potassium and magnesium
- Stop opioids, anticholinergics, antidiarrhoeals and NSAIDs
- No full colonoscopy or contrast enema (perforation risk). CMV biopsy: flexible sigmoidoscopy only if seniors agree
- Pregnant: involve obstetrics now; do not withhold CT or surgery because of pregnancy
- Nil by mouth; NG tube if vomiting or ileus
- VTE prophylaxis with LMWH unless bleeding is severe
04Action Tests and history: look for the cause (all patients)
Do these now, together with resuscitation.
- CT abdomen and pelvis if perforation is possible
- Stool: C. difficile test, and culture or PCR. Recent travel: also microscopy and culture for amoebae
- Bloods: FBC, CRP, UEC, LFTs, albumin, magnesium, lactate, blood cultures, coagulation screen, group and crossmatch
- Ask about IBD, recent antibiotics, recent travel, immunosuppression, vascular risk, anticoagulants and antiplatelets
05Decision Perforation, peritonitis, shock, massive bleeding or deterioration?
Steroids and immunosuppression can hide peritonitis. Get a CT if in doubt.
- Free air or contained perforation on CT
- Peritonitis on examination
- Septic shock or rising vasopressor need
- Massive or ongoing haemorrhage
- If Yes
06Warning Yes (perforation, shock, bleeding or worse): emergency subtotal colectomy
No delay. IV broad-spectrum antibiotics now. Resuscitate in theatre and ICU. Do not defer for recent steroids, infliximab or ciclosporin. On an anticoagulant: stop it and reverse per local protocol; do not delay surgery.
- Subtotal colectomy with end ileostomy; leave the rectum. No anastomosis and no proctectomy now
- C. difficile positive or strongly suspected: also give vancomycin 500 mg oral or NG 6-hourly plus metronidazole 500 mg IV 8-hourly (adult)
- Rectal stump: closed in the pelvis, mucous fistula, or closed stump in the wound
07Action After colectomy: post-operative care
ICU or HDU at first
- Taper steroids; do not stop them suddenly
- C. difficile: continue vancomycin plus IV metronidazole (fulminant C. difficile regimen)
- Consider extended VTE prophylaxis
- Stoma care and nutrition
- Histology to confirm UC, Crohn's, C. difficile or ischaemia
- Discuss later options: pouch (IPAA), ileorectal anastomosis or permanent ileostomy
08Outcome Outcome
Early surgery improves survival. Delay beyond 1 day is linked to about 5 times higher mortality (ASCRS 2026).
If No09Decision No perforation or shock: what is the cause of the colitis?
Known or likely IBD / C. difficile without IBD / other or unknown cause
- Known or likely IBD
10Action IBD: colectomy indicated; IV corticosteroids now while surgery and GI decide
For IBD only. Adult doses. Do not wait for stool results. ASCRS 2026: toxic megacolon is an indication for emergent colectomy. A short medical trial only by joint senior surgical and GI decision.
- IV hydrocortisone 100 mg 6-hourly or IV methylprednisolone 60 mg daily (adult)
- C. difficile positive: keep steroids; add vancomycin 500 mg oral or NG 6-hourly plus metronidazole 500 mg IV 8-hourly (adult)
- Recent travel to an area where amoebiasis is endemic: add IV metronidazole until stool microscopy and culture are back (ID advice)
- CMV on biopsy: add IV ganciclovir with GI and ID advice (dose: see local guideline)
- Serial examination, vital signs, CRP and abdominal X-ray every 12 h
11Decision Stable and clearly improving at 24 h?
Less dilatation, fever and heart rate settling, no new peritonitis. Reassess every 12 h. Continuing past 24 h is a joint senior surgical and GI decision.
- Yes: continue treatment, joint review every 12 h
- No, or worse at any time: colectomy now
- If Yes
12Action Yes (improving at 24 h): continue treatment, joint review every 12 h
Only by joint senior surgical and GI decision. Colectomy at once if the patient gets worse at any stage.
- IBD: continue IV steroids and manage as acute severe colitis
- Infliximab or ciclosporin only after dilatation resolves, by joint IBD and surgical decision
- C. difficile: complete treatment; watch for relapse
- Plan follow-up and maintenance therapy
- Path rejoins step 08Shared downstream outcome
If No- No or worse
13Warning No clear improvement or worse: colectomy now
Do not delay for rescue drugs. Delay beyond 1 day raises mortality.
- No clear improvement in dilatation, fever or heart rate by 24 h
- Worse at any time: more dilatation, perforation, bleeding, shock
- Recent steroids, infliximab or ciclosporin are not a reason to wait
14Action Colectomy: subtotal colectomy with end ileostomy
Operation of choice. Minimally invasive only if stable and expertise allows. On an anticoagulant: stop it and reverse per local protocol; do not delay surgery.
- Remove the colon; leave the rectum
- End ileostomy
- Rectal stump: closed in the pelvis, mucous fistula, or closed stump in the wound
- No anastomosis and no proctectomy in the acute setting
- C. difficile: loop ileostomy with colonic lavage is an alternative in selected patients
- Path rejoins step 07Shared downstream outcome
- C. difficile, no IBD
15Action No IBD, C. difficile positive or strongly suspected: fulminant C. difficile
No corticosteroids. Keep antibiotics for sepsis, peritonitis or perforation. Surgical team reviews now. Adult doses.
- Vancomycin 500 mg orally or by NG tube 6-hourly (adult)
- Plus metronidazole 500 mg IV 8-hourly (adult)
- Ileus: also vancomycin 500 mg in about 100 mL sodium chloride 0.9% per rectum 6-hourly as a retention enema
- Lactate 5 mmol/L or more, WCC 25 x10^9/L or more, or shock: early colectomy
- Stop other antibiotics if possible; keep antibiotics for sepsis, peritonitis or perforation
- Path rejoins step 11Shared downstream outcome
- Other or unknown cause
16Action No IBD, not C. difficile (ischaemic, CMV, unknown): urgent specialist review
No corticosteroids unless IBD is confirmed. Surgical team leads. If in doubt, treat as not improving.
- Ischaemic colitis: surgical team decides on resection
- CMV colitis (immunosuppressed): IV ganciclovir with ID advice
- Infective colitis (stool culture or PCR, travel history): treat per result with ID advice
- Unknown cause: repeat C. difficile test; ask GI about IBD
- Treat as not improving if there is any doubt
- Path rejoins step 11Shared downstream outcome
Guideline Source
ASCRS Clinical Practice Guideline for the Surgical Management of Ulcerative Colitis (2026); ACG Clinical Guideline Update: Ulcerative Colitis in Adults (2025)
Clinical Safety Information
Clinical Decision Support — Not a Substitute for Clinical Judgment
Individual patient factors may require deviation from these recommendations.
Known Limitations
- Adults only. Children need paediatric surgical and IBD teams.
- ASCRS 2026 advises emergent colectomy for toxic megacolon; any medical trial is short (reassess by 24 h) and a joint senior surgical and GI decision.
- Corticosteroids are for IBD only. C. difficile without IBD, CMV and ischaemic colitis need cause-specific care.
- Pregnancy: involve obstetrics early; drug choices (for example ganciclovir) differ.
- Fulminant C. difficile doses follow IDSA/SHEA 2017. The Australasian (ASID 2025) and eTG texts were not available for comparison.
Contraindicated Populations
Children and adolescents under 18 years
Applicable Regions
USEUAU
AU: Fulminant C. difficile doses follow IDSA/SHEA 2017. Where local antimicrobial guidance (eTG Antibiotic) differs, follow local guidance. Lab units: WCC in x10^9/L.
EU: ECCO 2022 UC surgical guideline gives no separate toxic megacolon statement; BSG 2019 lists toxic megacolon as an indication for subtotal colectomy.
US: ACG 2025 and ASCRS 2026 apply.
Version 2Next review: 2027-09-30
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Frequently Asked Questions
What is the Toxic Megacolon Management (ASCRS/ACG)?
The Toxic Megacolon Management (ASCRS/ACG) is a emergency clinical algorithm for Colorectal Surgery. It provides a structured decision tree to guide clinical decision-making, based on ASCRS Clinical Practice Guideline for the Surgical Management of Ulcerative Colitis (2026); ACG Clinical Guideline Update: Ulcerative Colitis in Adults (2025).
What guideline is the Toxic Megacolon Management (ASCRS/ACG) based on?
This algorithm is based on ASCRS Clinical Practice Guideline for the Surgical Management of Ulcerative Colitis (2026); ACG Clinical Guideline Update: Ulcerative Colitis in Adults (2025) (DOI: 10.1097/DCR.0000000000004290).
What are the limitations of the Toxic Megacolon Management (ASCRS/ACG)?
Known limitations include: Adults only. Children need paediatric surgical and IBD teams.; ASCRS 2026 advises emergent colectomy for toxic megacolon; any medical trial is short (reassess by 24 h) and a joint senior surgical and GI decision.; Corticosteroids are for IBD only. C. difficile without IBD, CMV and ischaemic colitis need cause-specific care.; Pregnancy: involve obstetrics early; drug choices (for example ganciclovir) differ.; Fulminant C. difficile doses follow IDSA/SHEA 2017. The Australasian (ASID 2025) and eTG texts were not available for comparison.. Individual patient factors may require deviation from these recommendations.
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