Ulcerative Colitis

Ulcerative Colitis

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Ulcerative colitis (UC) is a chronic inflammatory disease of the large intestine which may cause tissue loss and bleeding.

The disease might only affect the distal part of the colon, the rectum (ulcerative proctitis) or the left colon (left colitis) or the entire colon up to the cecum (pancolitis). It does not involve the small bowel - however mild inflammation has been sometimes reported in the terminal ileum.

In contrast to Crohn's disease, which tends to cause narrowing of the lumen, UC causes thinning and friability of the mucosa, which tends to bleed easily. In fact, its major clinical feature is blood loss from the rectum. As with Crohn's disease, UC is characterized by periods of flares alternated by inactivity.


Interior of diseased colon

The image above shows a colon affected by ulcerative colitis.

Generally, the tests necessary for diagnosis are the same in UC as in Crohn's disease: endoscopy, histology, clinical picture and blood/stool tests. Radiology plays a lesser role in UC because the disease does not affect the small bowel, therefore a colonoscopy is generally sufficient for diagnosis.

By contrast with Crohn's disease, endoscopy in UC shows shallow ulcerations and a very friable and easily bleeding mucosa. Histology shows inflammation only in the most superficial layers of the intestinal wall (by contrast with Crohn's disease which involves the deeper layers as well). The blood and stool tests (C-Reactive Protein, fecal calprotectin and lactoferrin) are non-specific and show inflammation.


Unlike with Crohn's disease, there is not usually pain associated with UC except for occasional cramps before the passage of stool. Usually the patient presents with several days or weeks history of bleeding diarrhea (unformed stool, several bowel motions per day). Often mucous is present in the stool. Sometimes the patient complains of tenesmus (the feeling of incomplete evacuation and continuous stimulus to move the bowels). As in Crohn's disease there may be low-grade fever, weight loss, deep fatigue, loss of appetite.

Complications of UC do not include intestinal obstruction but might include perforation when the disease involves the entire colon and is not under medical control. The patient can become severely ill, with severe pain and high fever.

A complication more frequent in UC than in Crohn's disease is cancer of the colon if the disease is very long standing and involves the entire large intestine. However, such a complication is usually the result of poor medical control of the disease and its frequency has significantly decreased with current medical treatment options.


In uncomplicated forms of UC, a specific intestinal anti-inflammatory agent - mesalamine and analogues - is usually effective. If the disease is localized only in the rectum topical forms of mesalamine (such as enemas and suppositories) might also be effective. Typical steroids such as cortisone should only be used, as in Crohn's disease, during flares and for limited periods of time (given their long term side effects). Immunosuppressants such as azathioprine/6-mercaptopurine can also be effective if mesalamine alone fails.

Biologics are also used in UC and they are similar to those used in Crohn's disease with some newer additions such as golimumab. In case biologics fail, surgery is usually the option of choice although still more biologics are being studied and will shortly be approved for this indication. Surgery essentially consists of total colectomy (removal of the entire colon) with either a permament stoma (bag) or a surgically created 'pouch' from the small bowel (which serves the function of the rectum).