Introduction

In inflammatory bowel diseases, the intestine (bowel) becomes inflamed, often causing recurring abdominal cramps and diarrhea.

The two primary types of inflammatory bowel disease are Crohn's disease and ulcerative colitis. These two diseases have many similarities and sometimes are difficult to distinguish from each other. However, there are several differences. For example, Crohn's disease can affect almost any part of the digestive tract, whereas ulcerative colitis almost always affects only the large intestine. The cause of these diseases is not known. More recently recognized inflammatory bowel diseases include collagenous colitis, lymphocytic colitis, and diversion colitis.

To make a diagnosis of inflammatory bowel disease, a doctor must first exclude other possible causes of inflammation. For example, infection with parasites or bacteria may cause inflammation. Therefore, the doctor performs several tests. Stool samples obtained during a sigmoidoscopy (see Section 9, Chapter 119) are analyzed for evidence of a bacterial or parasitic infection (acquired during travel, for example). Blood samples can determine the presence of a parasitic infection as well, or of a second infection resulting from antibiotic use (see Section 9, Chapter 127). A doctor also checks for sexually transmitted diseases of the rectum, such as gonorrhea, herpesvirus infection, and chlamydial infection. Tissue samples may be taken from the lining of the rectum and examined microscopically for evidence of colorectal cancer and other diseases that sometimes cause bloody diarrhea. Other possible causes of inflammation that a doctor tries to exclude are ischemic colitis, which occurs more often in people older than 50; pelvic inflammatory disease, ectopic pregnancy, and ovarian cysts and tumors in women; celiac disease; and tropical sprue.