Ulcerative Colitis
Ulcerative colitis (UC) is a chronic inflammatory condition of the colon and rectum, and one of the two most common forms of inflammatory bowel disease (along with Crohn’s disease). UC is characterized by continuous inflammation that starts in the rectum and extends upward for a variable distance, involving only the inner lining (mucosa) of the colon. Symptoms typically include bloody diarrhea, urgency, cramping abdominal pain, and, in more severe cases, fever, weight loss, and complications such as severe flares or, over the long term, increased risk of colon cancer. Treatment has advanced substantially with the availability of newer medications, and surgery (typically total colectomy with a J-pouch) can be curative when medical management is inadequate or when specific complications develop.
What is it?
Ulcerative colitis (UC) is a chronic inflammatory condition of the colon and rectum. It is one of the two most common forms of inflammatory bowel disease (IBD), along with Crohn’s disease. UC has several characteristic features that distinguish it from other conditions and, in particular, from Crohn’s disease:
Involvement is limited to the colon and rectum. UC does not affect the small intestine, esophagus, stomach, or other parts of the gastrointestinal tract. (Backwash ileitis, a mild inflammation of the terminal ileum, can occasionally occur in patients with pancolitis but is distinct from Crohn’s ileitis.)
Inflammation is continuous, starting from the rectum and extending upward for a variable distance without skip areas. This is a key distinguishing feature from Crohn’s disease, which typically has patchy involvement with skip lesions.
Inflammation is limited to the inner lining (mucosa) of the bowel and does not extend through the full thickness of the bowel wall. This is another key distinguishing feature from Crohn’s disease. Because of this, complications such as fistulas and abscesses are much less common in UC than in Crohn’s disease.
UC is classified by the extent of colonic involvement:
– Proctitis—involvement limited to the rectum
– Left-sided colitis (also called distal colitis)—involvement extending from the rectum to the splenic flexure (the bend where the colon changes direction in the upper left abdomen)
– Extensive colitis or pancolitis—involvement extending proximal to the splenic flexure, potentially involving the entire colon
The extent of involvement has important implications for symptoms, complications, treatment approach, and long-term surveillance (particularly for cancer risk).
The exact cause of UC is not fully understood but appears to involve an abnormal immune response to intestinal bacteria in genetically susceptible individuals, influenced by environmental factors. Multiple genes have been associated with increased risk, and family history is a significant risk factor. Environmental factors include the intestinal microbiome and, interestingly, smoking status (former smokers have an increased risk of UC after quitting, and active smoking appears to reduce risk—though smoking’s overall health effects far outweigh any potential UC-related benefit, and it is never recommended). Certain infections and medications may trigger or worsen UC in some patients.
UC typically follows a chronic course with periods of active symptoms (flares) alternating with periods of few or no symptoms (remission). The severity, frequency, and pattern of flares vary significantly among patients. Effective treatment can significantly reduce the frequency and severity of flares and maintain remission.
Symptoms of UC depend on the extent and severity of disease.
Common symptoms include:
– Bloody diarrhea (often frequent, sometimes with mucus). This is a hallmark of UC and typically more prominent than in Crohn’s disease, though occasional cases of very distal proctitis may present without significant diarrhea and predominantly with rectal bleeding
– Urgency to have bowel movements
– Cramping abdominal pain (often relieved by bowel movements)
– Sensation of incomplete emptying (tenesmus)
– Rectal bleeding
– Fatigue
More severe symptoms during flares may include high fever, unintended weight loss, dehydration, severe abdominal pain, and, in the most severe cases, symptoms of a severe flare or complications such as toxic megacolon or perforation, which require urgent evaluation.
Extraintestinal manifestations—symptoms outside the bowel that are related to the underlying immune process—can occur in UC. These may include:
– Joint pain and inflammation, including peripheral arthritis and axial arthritis (such as sacroiliitis and ankylosing spondylitis)
– Skin conditions including erythema nodosum (tender red bumps typically on the shins) and pyoderma gangrenosum (a rarer more severe skin condition)
– Eye inflammation (uveitis, episcleritis)
– Primary sclerosing cholangitis (PSC)—a chronic inflammatory condition of the bile ducts that is strongly associated with UC and has significant implications for evaluation, surveillance, and long-term outcomes
– Osteoporosis
– Increased risk of blood clots, particularly during flares
Diagnosis of UC typically involves several components.
Colonoscopy with biopsy is the primary diagnostic tool. It allows direct visualization of the colon and rectum, identification of the characteristic continuous pattern of inflammation starting from the rectum, and biopsy for confirmation. Typical endoscopic features include loss of normal vascular pattern, erythema (redness), edema, granularity, friability (easy bleeding), erosions, and, in more severe cases, ulcers. Inflammation appears continuous, and there is typically a clear demarcation between involved and uninvolved areas. Biopsies help confirm the diagnosis and distinguish UC from other conditions.
Sigmoidoscopy (which examines the rectum and lower colon) is often used during severe flares when full colonoscopy may not be safe (because of the risk of perforation) but visualization and biopsy are still needed.
Blood tests typically include complete blood count (which may show anemia and elevated white blood cell count), inflammatory markers (C-reactive protein, or CRP, and erythrocyte sedimentation rate, or ESR), kidney and liver function, and, when appropriate, tests for nutritional deficiencies (iron, vitamin D, and others) and screening for infections that could complicate treatment.
Stool tests are important, particularly at initial evaluation and during flares. Fecal calprotectin is a marker of intestinal inflammation and can help distinguish UC from non-inflammatory conditions such as irritable bowel syndrome, and monitor disease activity over time. Stool cultures and testing for Clostridioides difficile are important to exclude infection, which can mimic or complicate UC.
Imaging (CT or MRI) is generally less central to UC diagnosis than to Crohn’s disease diagnosis but may be useful for evaluation of complications such as toxic megacolon or perforation, or for evaluation of extraintestinal manifestations such as PSC.
Distinguishing UC from Crohn’s disease is important because management and long-term implications differ, though the distinction is not always immediately clear. In some cases, the diagnosis may become more apparent over time, and a small proportion of patients have features that cannot be definitively assigned to either condition (indeterminate colitis or IBD-unclassified). Distinguishing UC from other conditions—such as infectious colitis, ischemic colitis, medication-induced colitis, and, in the differential of first presentation, other conditions—is also important.
Severity assessment during a flare uses various scoring systems that combine clinical features (stool frequency, blood in stool, systemic features) and, in some settings, laboratory and endoscopic findings. This helps guide treatment intensity.
Important to Know
Management of ulcerative colitis has advanced substantially over the past two decades with the availability of newer medications and more sophisticated treatment strategies. Care is best coordinated by gastroenterologists (particularly those with IBD expertise), often involving multidisciplinary teams including colorectal surgeons, nutritionists, and, when needed, other specialists.
Modern UC management increasingly focuses on early effective treatment to achieve deep remission (including mucosal healing) and prevent complications. Goals of treatment include:
– Controlling active inflammation (inducing remission)
– Maintaining remission over the long term
– Healing the bowel lining (mucosal healing)
– Preventing complications
– Preserving quality of life
– Reducing the long-term risk of colon cancer
Medications for UC include several classes:
Aminosalicylates (5-aminosalicylic acid, or 5-ASA compounds, including mesalamine and others) are first-line treatment for mild-to-moderate UC. They are available in various formulations for different regions of the colon:
– Oral formulations, with different formulations releasing medication at different points in the GI tract
– Rectal formulations (suppositories for proctitis, enemas for left-sided disease) are highly effective for topical treatment of the lower colon and rectum
– Combined oral and rectal therapy is often more effective than either alone for appropriate patients
Corticosteroids (such as prednisone, methylprednisolone, and, for lower GI-limited effect, budesonide MMX and others) are effective for treating flares but are not appropriate for long-term maintenance due to significant side effects. They are typically used for induction of remission and then tapered.
Immunomodulators (such as azathioprine, 6-mercaptopurine, and methotrexate) are used to maintain remission and to reduce corticosteroid needs, though methotrexate is more commonly used in Crohn’s disease than UC. They act more slowly than corticosteroids and are generally started with the expectation of long-term use.
Biologic therapies have transformed UC treatment and include several classes:
– Anti-TNF agents (infliximab, adalimumab, golimumab, and, less commonly for UC, certolizumab) target inflammatory signaling
– Anti-integrin agents (vedolizumab) specifically target immune cell trafficking to the gut
– Anti-IL-12/23 agents (ustekinumab) target other inflammatory pathways
– Anti-IL-23 agents (mirikizumab, risankizumab, guselkumab) more specifically target the IL-23 pathway
– Others in this rapidly evolving category
Small molecule targeted therapies:
– JAK inhibitors (such as tofacitinib and upadacitinib) block intracellular inflammatory signaling
– Sphingosine-1-phosphate (S1P) receptor modulators (such as ozanimod and etrasimod) affect immune cell trafficking
Treatment selection depends on the extent of disease, severity, response to prior treatments, patient factors (including preferences, comorbidities, insurance coverage, and, in appropriate patients, planning for pregnancy), and specific characteristics. Modern approaches often involve early treatment with more effective agents in patients with high-risk features rather than a step-wise approach that begins with milder medications. Certain agents have particular strengths in specific scenarios—for example, tofacitinib and upadacitinib work rapidly for severe flares.
Acute severe ulcerative colitis is a specific severe flare pattern that typically requires hospitalization, intravenous corticosteroids, close monitoring for complications, and, if inadequate response is seen within 3–5 days, escalation to rescue therapy (typically infliximab, cyclosporine, or, in some settings, tofacitinib) or surgery. Careful attention to complications, particularly infection and toxic megacolon, is essential.
Regular monitoring during treatment includes clinical assessment, blood tests, stool tests (particularly fecal calprotectin), and periodic endoscopy to assess mucosal healing.
Surgery has an important role in UC and, unlike in Crohn’s disease, can be curative because the disease is limited to the colon and rectum. Indications for surgery include:
– Medically refractory disease
– Acute severe colitis not responding to medical rescue therapy
– Complications such as toxic megacolon or perforation
– Dysplasia (precancerous changes) or colon cancer
– Patient preference
Restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA, or “J-pouch”) is the most common current surgical approach and typically involves two or three stages:
– Total proctocolectomy (removal of the entire colon and rectum)
– Construction of a reservoir from the terminal ileum (usually shaped as a “J”)
– Connection of this reservoir to the anal canal, preserving natural continence for many patients
– Temporary diverting ileostomy during healing, typically reversed a few months later
The J-pouch approach allows bowel movements through the natural anal route, without a permanent stoma. Long-term function is generally good but often involves several bowel movements per day, and pouchitis (inflammation of the pouch) is a possible complication that can require ongoing treatment.
For patients who prefer or require it, total proctocolectomy with permanent end ileostomy (an opening on the abdominal wall with an external bag for stool collection) is an alternative. This approach avoids the potential complications of a J-pouch but requires permanent stoma care.
Cancer surveillance is important, particularly for patients with long-standing UC and, especially, those with extensive disease and/or associated primary sclerosing cholangitis (PSC). The risk of colon cancer in UC increases with duration of disease, extent of disease, and severity of inflammation over time. Regular surveillance colonoscopy with careful examination and biopsies (often with modern techniques such as chromoendoscopy or high-definition colonoscopy with targeted biopsies of visible lesions) is recommended. The specific frequency and approach are individualized based on disease duration, extent, presence of PSC, and other factors. For patients with PSC and UC, more intensive surveillance is warranted from the time of diagnosis. Detection of dysplasia (precancerous changes) may prompt more intensive follow-up, endoscopic removal of specific lesions, or, in some cases, consideration of proctocolectomy.
Management of extraintestinal manifestations is often coordinated with the treatment of the underlying UC, as many extraintestinal symptoms improve with control of the underlying disease. PSC follows its own course and requires specific management, often coordinated with hepatologists.
Nutritional support is important for many patients, particularly during flares or with significant weight loss. Consultation with dietitians is valuable.
Care during pregnancy in patients with UC requires special attention, and coordination with gastroenterology, obstetrics, and, when appropriate, maternal-fetal medicine is important. Most UC medications are compatible with pregnancy, and active UC during pregnancy generally poses more risk than well-controlled disease. Family planning is best discussed before pregnancy when possible.
For patients considering fertility preservation before treatment or surgery, coordination with reproductive medicine is important. J-pouch surgery is associated with some fertility considerations, particularly in women (with reports of reduced fertility, though usually preserved with modern approaches).
Vaccinations are particularly important for patients with UC, especially those on immunosuppressive therapy. Live vaccines have specific considerations, and coordination with primary care is important.
Mental health considerations are important, as UC can significantly affect quality of life. Support groups and organizations focused on IBD (such as the Crohn’s & Colitis Foundation) provide valuable information, community, and resources.
Care is typically coordinated by gastroenterologists with IBD expertise, and often involves multidisciplinary teams. Imaging, laboratory, endoscopic, and clinical findings are interpreted alongside the patient’s symptoms, examination, and broader clinical context rather than in isolation.
Patient education plays an essential role. Understanding the diagnosis, the extent of disease, the rationale for the treatment plan, the importance of medication adherence, the meaning of monitoring tests, warning signs of flares or complications, the importance of vaccinations, cancer surveillance recommendations, and, when relevant, the considerations for surgery or pregnancy all contribute to better outcomes.
Red flag symptoms include severe abdominal pain, significant abdominal distention (which may suggest toxic megacolon, particularly during a flare), significant gastrointestinal bleeding, high fever with signs of severe infection or sepsis (particularly in patients on immunosuppressive therapy), sudden severe abdominal pain (which may suggest perforation), signs of severe dehydration, severe joint pain with fever, sudden vision changes with severe eye pain, sudden severe headache or unusual symptoms in immunosuppressed patients, and rapid clinical deterioration. These warrant prompt or urgent medical evaluation.