Ulcerative colitis is one of the two main types of inflammatory bowel disease (IBD). The other is Crohn’s disease. Lymphocytic colitis and collagenous colitis are also forms of inflammatory disease but are very rare.

What is ulcerative colitis?

Ulcerative colitis is a disease of the large bowel (the colon and rectum) that is characterised by inflammation of the mucus membrane that lines the inner wall of the bowel. The disease may be confined to the rectum, known as proctitis, or may extend the length of the large intestine, known as pan-colitis. It is a chronic disease with no known cure, but it can often lay dormant, in remission, for months or even years at a time in between flare-ups. Ulcerative colitis can be managed, and removal of the colon (if control treatments fail) will prevent the disease returning.

What causes ulcerative colitis?

The cause of ulcerative colitis is not known. Many specialists consider it to be an autoimmune condition (in which the body’s own defences attack healthy tissue). Some research has suggested a connection with some of the bacteria that normally live in the gut, but the jury is still out.

A number of factors have been identified as possibly playing a role in ulcerative colitis, including genetic traits, environmental elements, diet and stress, and extensive research is underway to try to narrow down the exact cause of the disease.

Symptoms of ulcerative colitis

The symptoms of ulcerative colitis can vary from mild and manageable to severe and life-changing, and include:

  • Frequent and urgent diarrhoea
  • Blood and mucus in the stools
  • Bleeding from the rectum
  • Abdominal pain

These symptoms usually come and go, with long periods of normal bowel function in between.

Diagnosing ulcerative colitis

Since ulcerative colitis occurs exclusively in the rectum and colon, initial diagnosis can be made using flexible sigmoidoscopy, which examines the rectum and lower colon, or colonoscopy, in which a flexible camera is inserted into the rectum and used to examine the full length of the colon.

Small samples of the gut lining may be taken during these investigations for further examination under a microscope. Tests are also done on blood and stool samples both to identify the markers for the disease, as well as to check for anaemia and other possible complications.

Complications of ulcerative colitis

Complications of ulcerative colitis are rare, but can include:

  • Primary sclerosing cholangitis – which damages the bile duct.
  • Bowel cancer – people with ulcerative colitis have an increase risk of bowel cancer, which rises over time from 1 in 50 after ten years, to 1 in 6 after 30 years.
  • Toxic megacolon – a severe attack of ulcerative colitis may lead to a severe and life-threatening condition that causes the colon to swell.

Treating ulcerative colitis

Find out more about how ulcerative colitis is treated.