I.

Introduction

Colitis, inflammation of the inner lining of the colon (the main part of the large intestine, or bowel), or of the rectum (the terminal segment of the large intestine). Colitis is not, in itself, a disease, but is a general term covering any of the several diseases in which the colon is inflamed. These include ulcerative colitis, Crohn’s disease, amoebic or bacillary dysentery, some cases of AIDS, and some worm infestations. The long-term use of powerful, broad-spectrum antibiotics (antibiotics that destroy a wide range of bacteria) can also cause colitis.

II.

Ulcerative Colitis

Ulcerative colitis, a condition of unknown cause, occurs all over the world with an incidence varying from 3 per 100,000 of the population to over 11 per 100,000. In the United Kingdom, reported cases range from 6.5 per 100,000 in Oxford to 11.3 per 100,000 in Aberdeen. The condition often runs in families. In ulcerative colitis the inflammation always involves the rectum, but frequently extends further up the bowel to the colon. The mucous membrane lining of the bowel is, at first, merely reddened and granular. However, as the condition becomes more severe numerous tiny craters, or ulcers, appear. These may then enlarge and deepen and extend widely into the wall of the bowel. As in most forms of severe colitis the principal symptoms are diarrhoea and the passage of blood and mucus, and sometimes pus. Abdominal pain may be present but is not a major feature.

III.

Crohn’s Disease

In Crohn’s disease, which is also of unknown cause, inflammation may involve any part of the digestive tract from the mouth to the anus. Usually, however, a specific segment of the colon is affected. The lining becomes red and ulcerated and, because the inflammation affects the full depth of the bowel wall, this becomes greatly thickened and shortened and the passage usually narrows.

IV.

Diagnosis

Diagnosis of the various forms of colitis is made on the basis of the patient’s medical history, the presence or absence of specific infective organisms in the faeces, the characteristic reddened appearances of the bowel lining on internal examination with an endoscope, and, if necessary, laboratory microscopic examination of samples taken on endoscopy. Types of colitis resulting from infection by specific organisms such as the amoeba Entamoeba histolytica, which causes amoebic dysentery, or Shigella bacteria, which cause bacillary dysentery, are readily diagnosed by the identification of these causal agents.

V.

Treatment

In infective cases of colitis, treatment is by drugs used to destroy the organisms concerned. Corticosteroid drugs, all of which have a powerful anti-inflammatory effect, are extensively used in both ulcerative colitis and Crohn’s disease. These drugs can dispel the inflammation, while various other drugs, such as the sulpha drug sulphasalazine, can often prevent recurrences of short-term (acute) attacks.

Surgical removal of part or all of the colon may be necessary if medical treatment fails or if complications such as narrowing of the colon make it necessary. In ulcerative colitis, surgery may also be necessary where there is an increased risk of cancer in patients who have suffered from severe and extensive disease for many years.