Ulcerative colitis is an unceroinflammatory disease limited to the colon and affecting only the mucosa and submucosa except in the most severe cases. In contrast to Crohn disease, ulcerative colitis extends in a continious fashion proximally from the rectum. Well-formed granulomas are absent. Similar to Crohn disease, ulcerative colitis is a systemic disorder associated in some patients with migratory polyarthritis, sacroiliitis, ankylosing spondylitis, uveitis hepatic involvement (pericholangitis and primary sclerosing cholangitis and skin lesions.

Epidemiology

Ulcerative colitis is global in distribution and varies in incidence relative to Crohn disease, supporting the concept that they are separate disease. In the United States, incidence is about 4 to 12 per 100,000 population slightly greater than Crohn disease. As with Crohn disease, the incidence of this condition has risen in recent decades. In the United States, it is more common among whites than among blacks and women are affected more often than men. The onset of disease peaks between the ages of 20 and 25 years but the conditionmay arise in both younger and considerably older individuals.

Clinical Features

Ulcerativecolitis typically presents as a relapsing disorder marked by attacks of bloody mucoid diarrhea that may persist for days , weeks, or months, then subside, only to recur after an asymptomatic interval of months to years or even decades. In the fortunate patient, the first attack is the last. At the other end of the spectrum, the explosive initial attack may lead to such serious bleeding and fluid and electrolyte imbalance as to constitute a medical emergency. In most patients, bloody diarrhea containing stringy mucus, accompanied by lower abdominal pain and cramps usually relieved by defecation, is the firsts manifestation of the disease. In a small number of patients, constipation may appear paradoxically, owing to disruption of normal peristalsis. Often the first attack is preceded by a stressful period in the patient's life. Spontaneously or more often after appropriate therapy these symptoms abate in the course of days to weeks. Flare-ups when they do occur may be precipitated by emotional or physical stress and rarely concurrent intraluminal growth exterotoxin forming C difficile. Sudden cessation of bowel function with toxic dilation (toxic megacolon)rarely develops with severe acute attacks; perforation is a potentially lethal event.

About 60% of patients have clinically mild disease. In these individuals, the bleeding and diarrhea are not severe and systemic signs and symptoms are absent. Almost all patients however, have at least one relapse during 10-year period about 30% of patients require colectomy with the first 3 years of onset because of uncontrollable disease.

The most feared long term complication of ulcerative colitis is cancer. There is a tendency for dysplasia to arise in multiple sites, and the underlying inflammatory disease may mask the symptoms and signs of carcinoma. Historically the risk of cancer is highest in patients with pancolitis of 10 or more years duration, in whom it exceeds by 20 fold to 30 that in a control population equivalent to an absolute risk of colorectal cancer 35 years after diagnosis of 30%. Screening programs of patients with ulceration of dysplasia and carcinoma is in fact quite low provided that initial examinations were negative for dysplasia.