Ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory bowel disease.

It specifically targets the colon and the rectum. This condition causes long-term inflammation and the formation of ulcers. Ulcers are small sores on the lining of the gut. Unlike Crohn's disease, which can appear in patchy "skip lesions," UC inflammation is usually continuous. It typically starts in the rectum and spreads upward through the colon. Understanding UC is vital because it affects both digestion and the entire body. It is one of two main types of inflammatory bowel disease (IBD).

The symptoms of UC often occur in intermittent waves. During a "flare," symptoms become active and more intense. Many patients experience diarrhea mixed with blood, a condition called hematochezia. About 90% of people with UC experience rectal bleeding. Another common symptom is bowel urgency, where a person feels a sudden need to use the bathroom. Some may experience rectal tenesmus. This is an urgent desire to evacuate the bowels even when very little stool is present. This sensation can sometimes be mistaken for constipation.

Doctors classify UC based on how much of the colon is involved. Proctitis is inflammation limited to the rectum. Proctosigmoiditis involves the rectum and the sigmoid colon. Left-sided colitis occurs when inflammation reaches the descending colon. Extensive colitis involves areas proximal to the descending colon. Pancolitis is the most widespread form, affecting the entire colon from the rectum to the cecum. About 17% of people with UC also develop ileitis, which is inflammation of the ileum. This is often called "backwash ileitis" when it occurs during pancolitis.

The exact cause of ulcerative colitis remains unknown. Scientists have several theories regarding why it develops. One theory suggests immune system dysfunction, where the body attacks its own tissues. Genetics may also play a significant role in who develops the condition. Changes in the normal gut bacteria might contribute to the inflammation. Environmental factors and a Western diet are also being studied. Interestingly, removing the appendix at an early age may offer some protection.

The severity of UC is measured by symptoms and biological markers. Doctors use tools like the Mayo Score to classify disease as mild, moderate, or severe. Mild disease usually involves fewer than four stools per day. Severe disease can involve more than six stools daily and frequent bloody stools. High levels of inflammatory markers, such as C-reactive protein (CRP), often indicate more severe illness. In very rare, acute-severe cases, the colon can dilate abnormally. This is called toxic megacolon and is a medical emergency.

UC is a systemic condition, meaning it can affect parts of the body far from the gut. Between 6% and 47% of patients experience extra-intestinal manifestations. For example, about 8% of people develop oral issues like aphthous stomatitis. These are benign, noncontagious sores in the mouth. The disease can also cause eye inflammation, such as uveitis or episcleritis. If left untreated, eye inflammation can lead to permanent vision loss. Some patients also experience joint pain or swelling, known as arthritis.

Skin issues are another common complication of UC. Erythema nodosum causes red, tender nodules on the shins in up to 3% of patients. Another condition, pyoderma gangrenosum, involves deep, painful skin ulcers. This affects about 1% of patients and often occurs independently of gut inflammation. To manage these symptoms, doctors use various medications. These include aminosalicylates, steroids, and immunosuppressants. In severe cases, surgery to remove the colon and rectum may be necessary. This surgical removal generally cures the condition.