Acute Severe Ulcerative Colitis (ASUC)

Acute severe ulcerative colitis is a life‑threatening flare that needs hospital care. The goals are to confirm severity, rule out infection, start intravenous (IV) corticosteroids, and make a clear day‑3 decision about rescue therapy or surgery. Early flexible sigmoidoscopy, blood clots prevention, and close daily monitoring are standard. Timely surgery saves lives when medicines fail. (ovid.com)

Key takeaways

• ASUC is defined by frequent bloody stools with signs of systemic toxicity using modified Truelove and Witts criteria. (ovid.com)

• Give IV methylprednisolone 40–60 mg daily, avoid routine antibiotics, and reassess daily. (gastro.org)

• Do early flexible sigmoidoscopy within 24–72 hours and biopsy to evaluate for cytomegalovirus. Start pharmacologic blood clot prevention. (gi.org)

• If not improving by day 3, use infliximab or cyclosporine as rescue. Use Oxford day‑3 criteria to predict steroid failure. (gastro.org)

• Call surgery early. Toxic megacolon, perforation, severe hemorrhage, or failure of rescue are indications for urgent colectomy. (journals.lww.com)

What qualifies as ASUC

ASUC means six or more bloody stools per day plus at least one toxicity sign. Toxicity signs include fever, fast heart rate, anemia, or elevated inflammatory markers such as C‑reactive protein. About 15 to 25 percent of people with ulcerative colitis will be hospitalized at some point for a severe flare. (ovid.com)

The first 24 hours: assessment and supportive care

• Confirm severity and exclude infection. Send stool for Clostridioides difficile testing, and consider bacterial cultures based on setting. Get complete labs and a plain abdominal X‑ray if distension or tenderness is present. (pmc.ncbi.nlm.nih.gov)

• Perform flexible sigmoidoscopy within 24 to 72 hours. Assess endoscopic severity and obtain biopsies to evaluate for cytomegalovirus colitis. Early sigmoidoscopy is linked to shorter stays and earlier rescue when needed. (gi.org)

• Start pharmacologic venous thromboembolism (VTE) prophylaxis unless contraindicated. Low molecular weight heparin is preferred. Continue during hospitalization. (pmc.ncbi.nlm.nih.gov)

• Avoid nonsteroidal anti‑inflammatory drugs, opioids, and anticholinergic agents. These can worsen dilation and outcomes. Use acetaminophen and nonpharmacologic measures for pain. (journals.lww.com)

• Involve gastroenterology, colorectal surgery, nursing, pharmacy, and nutrition early. Multidisciplinary care improves safety. (wjes.biomedcentral.com)

IV corticosteroids: the backbone of initial therapy

Use IV methylprednisolone 40–60 mg daily, or hydrocortisone 100 mg every 6 to 8 hours. Higher doses do not improve outcomes. Most responses appear within 3 days. Extending IV steroids beyond 7 to 10 days offers little benefit and increases risk. Monitor stool frequency, bleeding, vitals, and daily C‑reactive protein. (gastro.org)

Predicting steroid failure by day 3

The Oxford day‑3 criteria help identify patients likely to need colectomy. A stool frequency greater than eight per day, or three to eight with C‑reactive protein above 45 mg per liter on day 3, predicts a high risk of failure. Modern colectomy rates are lower, but these thresholds still flag concern and guide escalation. (academic.oup.com)

Rescue therapy when IV steroids are not enough

If there is no adequate improvement by day 3, initiate rescue therapy. Infliximab and cyclosporine are both effective. Comparative trials show similar short‑term outcomes, so the choice can be based on clinician experience, prior drug exposure, albumin level, and plans for long‑term maintenance. Routine adjunctive antibiotics are not recommended without proven infection. (gastro.org)

Rescue options at a glance

Notes on other agents: evidence for using tofacitinib or upadacitinib as inpatient rescue after steroid or infliximab failure is limited, so they are not routinely recommended in ASUC. (gi.org)

Special infections to consider: CMV and C. difficile

Cytomegalovirus can mimic or worsen ASUC. Diagnosis relies on tissue testing with immunohistochemistry, with or without tissue PCR. Biopsies from ulcer bases and edges increase yield. Blood PCR may support the diagnosis but cannot replace tissue. Treat proven CMV colitis with antivirals and manage IBD therapy case by case. (academic.oup.com)

When to involve surgery and what operation is done

Call colorectal surgery within the first 48 to 72 hours, and sooner if toxic megacolon, perforation, or severe bleeding is suspected. Failure to respond to optimal medical therapy within a few days, or clinical deterioration, are triggers for urgent operation. The preferred emergency procedure is subtotal colectomy with end ileostomy, leaving the rectum in place for possible reconstruction later. Early surgery reduces complications. (journals.lww.com)

After response: transition and follow‑up

If a clear clinical response occurs, convert to oral steroids with a taper, and transition to an effective maintenance therapy. Many patients continue infliximab if it was the rescue agent. After cyclosporine, transition to a maintenance biologic is common. Plan close follow‑up, biomarker monitoring, and a scope‑based assessment to confirm healing. (gastro.org)

FAQs

How fast should improvement be expected with IV steroids

Most responders improve within about 3 days. Lack of improvement by day 3 should prompt rescue therapy or surgical planning. (academic.oup.com)

Is anticoagulation safe if there is rectal bleeding

Yes, pharmacologic VTE prophylaxis is recommended for all hospitalized patients with IBD unless clearly contraindicated. It lowers clot risk without increasing severe bleeding in typical cases. (pmc.ncbi.nlm.nih.gov)

Can ASUC and C. difficile occur together

Yes. Test for C. difficile on admission. Treat proven infection with targeted antibiotics while continuing IBD management. (pmc.ncbi.nlm.nih.gov)

Do antibiotics help ASUC if no infection is found

No. Guidelines suggest against routine antibiotics in ASUC without infection. (gastro.org)