Surgery & Complications
Ulcerative colitis is unpredictable enough on its own. But beyond the day-to-day cycle of flares and remission, UC carries the risk of complications that range from manageable nuisances to genuine medical emergencies. Understanding which complications demand immediate action, which ones you can work through with your care team, and which ones require steady long-term monitoring can make a real difference in outcomes. This guide organizes the major UC complications by urgency so you know what to watch for and when to act.
Emergencies: When to Go to the Hospital
Some UC complications are time-sensitive. Recognizing them early can be lifesaving.
Toxic megacolon occurs when severe inflammation causes the colon to dilate rapidly and lose its ability to contract. The colon wall becomes dangerously thin and fragile, creating a risk of perforation. Symptoms include sudden severe abdominal pain, distension, fever above 101.5 F, and rapid heart rate. Toxic megacolon complicates about 5% of acute severe UC cases and requires immediate hospitalization. If the colon perforates, bacteria can leak into the abdominal cavity and cause sepsis. Treatment typically starts with IV steroids, bowel rest, and close monitoring, but emergency surgery may be necessary if the colon does not respond within 24 to 72 hours.
Bowel perforation can also occur independently of toxic megacolon during severe flares. A perforation allows intestinal contents to spill into the abdomen, triggering peritonitis, a life-threatening infection. Sudden, intense abdominal pain that worsens with movement, along with fever and a rigid abdomen, warrants an emergency room visit.
Blood clots are another underrecognized emergency. People with inflammatory bowel disease have roughly three times the blood clot risk of the general population. Chronic inflammation promotes clotting, and dehydration from active flares compounds the problem by thickening the blood. Deep vein thrombosis, or DVT, typically presents as swelling, pain, and warmth in one leg. A pulmonary embolism, where a clot travels to the lungs, causes sudden shortness of breath, chest pain, and lightheadedness. Both require immediate medical attention. Let your doctor know about your UC diagnosis if you ever visit an ER for these symptoms, since the connection is frequently overlooked.
Clostridioides difficile: A Complication That Mimics a Flare
C. difficile infection deserves its own category because it is both common in UC patients and dangerously easy to miss. The symptoms of a C. diff infection, including worsening diarrhea, abdominal cramping, and fever, overlap heavily with a UC flare. That overlap means patients and doctors sometimes treat what looks like a flare with immunosuppressive medications, which can actually make a C. diff infection worse.
Up to 47% of hospitalized UC patients test positive for C. difficile. The infection can develop after antibiotic use, but UC patients are vulnerable even without that trigger because chronic inflammation and immune-modulating medications alter the gut environment. In severe cases, C. diff can progress to fulminant colitis and toxic megacolon, with mortality rates between 38% and 80% in those extreme scenarios.
The takeaway: any unexpected worsening of symptoms, particularly if you have been hospitalized recently or taken antibiotics, should prompt C. diff testing before treatment decisions are made. Current guidelines recommend stool testing for every patient admitted with acute severe UC.
Post-Surgical Complications: Life After Colectomy
For patients who have had their colon removed and a J-pouch constructed, a different set of complications enters the picture.
Pouchitis, inflammation inside the J-pouch, is the most common post-surgical complication. It affects up to 50% of J-pouch patients, usually within the first two years after surgery, though it can develop at any point. Symptoms include increased frequency and urgency of bowel movements, abdominal pain, bleeding, and sometimes fever. A two-week course of antibiotics resolves most episodes. However, 10% to 15% of patients with acute pouchitis develop a chronic form that requires long-term antibiotics or biologic therapies.
Cuffitis is inflammation of the small strip of rectal tissue left behind during surgery. It produces symptoms similar to pouchitis and is treated with topical anti-inflammatory medications. Small bowel obstruction from post-surgical adhesions, bands of scar tissue that can form between organs, is another potential complication that may cause cramping, bloating, nausea, and vomiting.
If you have a J-pouch and notice a sustained change in your bowel pattern, particularly increased frequency or new urgency, report it to your gastroenterologist rather than assuming it will resolve on its own.
Complications That Build Slowly: Long-Term Monitoring
Several UC complications develop gradually and require ongoing surveillance rather than urgent intervention.
Primary sclerosing cholangitis, or PSC, is a chronic liver condition in which the bile ducts become inflamed and scarred. PSC is diagnosed in 2% to 14% of IBD patients, and its relationship with UC is complex enough that researchers debate whether PSC-IBD should be classified as its own distinct condition. PSC often progresses silently, with abnormal liver enzymes appearing on blood tests before any symptoms develop. Fatigue, itching, and jaundice are later signs. For UC patients with PSC, surveillance colonoscopies should begin at the time of PSC diagnosis and be repeated annually, because the combination carries an elevated colorectal cancer risk.
Colorectal cancer risk increases in patients who have had extensive UC for eight years or more. Surveillance colonoscopies are recommended every one to three years depending on individual risk factors such as family history, degree of inflammation, and the presence of strictures or pseudopolyps. The encouraging news is that the relative risk of colorectal cancer in UC patients has actually been declining, likely due to better biologic therapies and improved surveillance strategies. Chromoendoscopy, a technique that uses dye to highlight abnormal tissue during colonoscopy, has improved detection of precancerous changes.
Osteoporosis affects bone density in up to 60% of people with UC. Corticosteroids like prednisone are a major contributor, as prolonged use interferes with the body's ability to maintain healthy bones. If you have taken corticosteroids for extended periods, ask your doctor about a bone density scan, or DEXA scan, and discuss calcium and vitamin D supplementation.
Anemia is one of the most common UC complications, affecting about one in three patients. It results from a combination of chronic blood loss in the GI tract and impaired iron absorption caused by inflammation. Fatigue, weakness, and shortness of breath during routine activities are hallmark symptoms. Iron studies through a simple blood test can identify whether supplementation or IV iron infusions are needed.
Structural Changes: Strictures and Pseudopolyps
Long-standing UC can produce physical changes in the colon that affect disease management.
Pseudopolyps are islands of regenerated tissue that form after repeated cycles of ulceration and healing. They are the most common local complication of UC and are generally benign. However, large pseudopolyps, those exceeding 1.5 centimeters, can occasionally cause bleeding or partial obstruction. Their presence also complicates cancer surveillance because they can make it harder to identify genuinely abnormal tissue during colonoscopy.
Strictures, or narrowing of the colon, occur in 1% to 11% of patients with long-standing disease. Unlike the strictures seen in Crohn's disease, which are usually caused by fibrosis, UC strictures always warrant investigation to rule out an underlying malignancy. Symptoms include cramping, bloating, and changes in stool caliber.
Knowing Your Baseline
The thread connecting all of these complications is that early recognition changes outcomes. Toxic megacolon caught early responds far better to medical treatment. C. diff identified before immunosuppression is escalated avoids a dangerous clinical spiral. Anemia and osteoporosis treated proactively prevent compounding damage.
But recognizing a change requires knowing what your normal looks like. Tracking your symptoms consistently, including bowel frequency, urgency, energy levels, and any new pain patterns, gives both you and your care team a reference point. When something shifts, you can identify it faster and communicate it clearly. Aidy helps you build that baseline and spot the changes that matter, so you can have more informed conversations with your doctor and catch complications before they escalate.