Acute Severe Ulcerative Colitis (ASUC)

Acute severe ulcerative colitis (ASUC) is a life‑threatening flare of ulcerative colitis that almost always needs urgent hospital care. Management centers on rapid assessment, high‑dose intravenous (IV) steroids, careful daily monitoring, and early decisions about “rescue” therapies or surgery if steroids do not work. Knowing these steps can help people with UC and their families understand what is happening in the hospital.

Key Takeaways

• ASUC is a medical emergency that usually requires hospital admission and close, daily review by an experienced IBD team.

• First‑line treatment is high‑dose IV corticosteroids, usually given for 3 to 5 days with clear goals for improvement.

• If IV steroids fail, “rescue” therapy with medicines like infliximab or cyclosporine is often used, with early input from colorectal surgeons.

• Surgery is urgent when there is toxic megacolon, perforation, uncontrolled bleeding, or failure of intensive medical therapy.

• Preventing blood clots, treating infections, and planning long‑term maintenance therapy are essential parts of ASUC care.

What is Acute Severe Ulcerative Colitis?

Acute severe ulcerative colitis is a sudden, major flare of UC that causes many bloody stools each day plus signs of whole‑body illness.

Typical features include:

• Very frequent stools, often more than 6 per day

• Visible blood and mucus in stool

• Severe urgency and cramping

• Fever, fast heart rate, or weakness

• Low blood counts or abnormal inflammatory blood tests

Clinicians often use scoring systems, such as the Truelove and Witts criteria or the Mayo score, to define ASUC and guide decisions. These tools combine stool frequency with blood tests and vital signs to estimate risk of needing surgery.

First Steps in the Hospital

Rapid assessment

On arrival, the hospital team usually:

• Reviews symptoms, current and past UC treatments, and prior surgeries

• Examines the abdomen for tenderness, guarding, or distension

• Checks vital signs (heart rate, blood pressure, temperature, oxygen levels)

Blood tests commonly include:

• Complete blood count (for anemia and infection)

• C‑reactive protein (CRP) and inflammatory markers

• Electrolytes, kidney and liver tests

• Albumin (a marker of nutrition and inflammation)

Stool tests look for infections that can mimic or worsen ASUC, especially Clostridioides difficile (C. diff). In patients already on strong immune‑suppressing medicines, doctors may also check for cytomegalovirus (CMV) in the colon.

Imaging and endoscopy

Most patients have:

• An abdominal X‑ray to look for toxic megacolon or perforation

• A flexible sigmoidoscopy without full bowel prep, to confirm active UC, rule out other causes, and obtain biopsies

Full colonoscopy is usually avoided in ASUC because it increases the risk of perforation.

Supportive care

Supportive care is as important as specific UC treatments. It may include:

• IV fluids and electrolytes

• Nutritional support, often starting with an easy‑to‑tolerate diet and using tube feeding or IV nutrition if needed

• Careful pain control while avoiding strong opioids when possible

• Stopping medicines that can worsen colitis, such as non‑steroidal anti‑inflammatory drugs (NSAIDs)

• Blood clot prevention with injectable blood thinners and compression devices, because people with ASUC have a high risk of clots

Antidiarrheal medicines like loperamide are usually avoided in ASUC because they can increase the risk of toxic megacolon.

First‑Line Treatment: Intravenous Steroids

How IV steroids are used

High‑dose IV corticosteroids are the standard first treatment for ASUC in adults and children, based on large international guidelines. Common choices include:

• Methylprednisolone once daily

• Hydrocortisone several times per day

Treatment usually lasts 3 to 5 days before a firm decision is made about next steps.

Steroids work by rapidly calming inflammation in the colon. Many patients experience fewer stools, less bleeding, and less pain within a few days.

Monitoring response

The care team checks for improvement every day by tracking:

• Stool number and presence of blood

• Abdominal pain, distension, and vital signs

• CRP and other blood markers

• X‑rays if there is concern about megacolon

By about day 3 of IV steroids, clinicians reassess using simple rules that combine stool frequency and CRP. Poor improvement by this point signals a high chance of needing rescue therapy or surgery.

If there is clear improvement, IV steroids are usually continued, then switched to oral steroids with a slow taper and a long‑term maintenance plan.

Rescue Therapy When Steroids Are Not Enough

When IV steroids fail or only give very limited benefit, guidelines recommend rescue therapy with a second‑line medicine, provided there is no emergency reason to go straight to surgery.

Two main options are commonly used:

Choice depends on prior treatments, other medical conditions, and center experience. For example:

• Someone who already failed an anti‑TNF drug may be steered toward cyclosporine or surgery.

• Someone who is anti‑TNF naïve may receive infliximab as rescue and then continue it as maintenance therapy.

Response to rescue therapy is again judged over several days, focusing on symptoms, labs, and signs of complications. Delay in starting rescue therapy after clear steroid failure increases the risk of poor outcomes, so early decisions are encouraged.

When Surgery is Needed

Early surgical involvement

Colorectal surgeons are usually involved early in ASUC, even if surgery is not immediately planned. This allows:

• Ongoing shared assessment of risk

• Time to explain possible operations and stoma care

• Fast action if the patient deteriorates

Absolute indications for urgent colectomy

Surgery is considered urgent or life‑saving when any of the following occur:

• Toxic megacolon: the colon becomes very swollen on imaging, with severe pain, fever, and systemic illness

• Perforation: a hole in the colon, with sudden severe pain and signs of infection or shock

• Uncontrolled bleeding: ongoing heavy bleeding or need for repeated blood transfusions

• Sepsis or organ failure despite best medical treatment

In these situations, waiting longer for medicines to work can be dangerous.

Failure of intensive medical therapy

Even without megacolon or perforation, surgery is often recommended when:

• There is little or no improvement after 3 to 7 days of IV steroids plus rescue therapy

• Symptoms remain very severe, with high stool frequency and blood

• Inflammatory markers stay high or worsen

• The person cannot safely leave the hospital without ongoing high‑dose steroids

Current guidelines emphasize that timely surgery in this setting is safer than prolonged unsuccessful medical therapy.

What Surgery Involves in ASUC

The usual emergency operation for ASUC is a subtotal colectomy with end ileostomy:

• Most of the colon is removed.

• The end of the small intestine is brought to the skin as a stoma, where stool empties into a bag.

• The rectum is often left in place at this stage and removed or connected later.

After recovery, some patients choose a second‑stage operation to create an ileal pouch‑anal anastomosis (IPAA or J‑pouch), which can remove the stoma in many cases. Others may decide to keep the ileostomy long term.

After an ASUC Hospitalization

Surviving an episode of ASUC is a major event. Follow‑up focuses on:

• Transitioning from IV to oral steroids, then tapering them safely

• Starting or optimizing maintenance therapy (such as a biologic or small‑molecule drug) to prevent future severe flares

• Monitoring for steroid complications, anemia, and nutritional deficits

• Psychological support, given the trauma of an emergency hospitalization or surgery

• Updating vaccinations and infection screening before continued immunosuppressive therapy

Long‑term, many people who have had ASUC will be followed more closely, with clear action plans for any future symptom spikes.

FAQs

How long do people usually stay in the hospital for ASUC?

Hospital stays vary, but many last about 7 to 10 days. Stays are shorter when IV steroids work quickly and longer when rescue therapy or surgery is needed.

Can ASUC happen if ulcerative colitis was previously mild?

Yes. Some people with previously mild or moderate UC can suddenly develop an acute severe flare, sometimes triggered by infection, medication changes, or unknown factors.

Why do hospitals give blood thinners when there is rectal bleeding?

ASUC greatly increases the risk of blood clots in the legs and lungs. Low‑dose blood thinners reduce this risk and are usually safe even with moderate rectal bleeding, although the team adjusts treatment if bleeding becomes heavy.

Is rescue therapy always tried before surgery?

Not always. If there is toxic megacolon, perforation, uncontrolled bleeding, or severe sepsis, surgery is usually the safest immediate option. Rescue therapy is mainly used when the person is very unwell but still stable enough to try intensive medical treatment first.