The two primary forms of inflammatory bowel disease (IBD), Crohn's disease (CD) and ulcerative colitis (UC), share many symptoms, but are treated very differently medically and surgically. In many cases, a trained gastroenterologist (armed with various test results) can determine whether a case of IBD is either CD or UC. However, there are cases where the diagnosis of one form of IBD over the other is very difficult. At times, a final diagnosis is possible only after an event during the course of the disease or its treatment makes the form of IBD readily apparent.
Patients with IBD may be very confused as to the differences between these diseases. As with any chronic condition, education is an important tool that can be used to become an active (rather than a passive) participant in one's own treatment plan. The main differences between UC and CD are described below.
Location of inflammation
In CD, the location of the inflammation may occur anywhere along the digestive tract from the mouth to the anus. In UC, the large intestine (colon) is typically the only site that is affected. However, in some people with UC the last section of the small intestine, the ileum, may also show inflammation.Symptoms
Many symptoms of UC and CD are similar, but there are some subtle differences. UC patients tend to have pain in the lower left part of the abdomen, while CD patients commonly (but not always) experience pain in the lower right abdomen. With UC, bleeding from the rectum during bowel movements is very common, and bleeding is much less common in patients with CD.Pattern of inflammation
The pattern that each form of IBD takes in the digestive tract is very distinct. UC tends to be continuous throughout the inflamed areas. In many cases, UC begins in the rectum or sigmoid colon, and spreads up through the colon as the disease progresses. In CD, the inflammation may occur in patches in 1 or more organs in the digestive system. For instance, a diseased section of colon may appear between two healthy sections.Appearance
During a colonoscopy or sigmoidoscopy, the physician can view the actual inside of the colon. In a colon that has CD activity, the colon wall may be thickened and, because of the intermittent pattern of diseased and healthy tissue, may have a "cobblestone" appearance. In UC, the colon wall is thinner and shows continuous inflammation with no patches of healthy tissue in the diseased section.Granulomas are inflamed cells that become lumped together to form a lesion. Granulomas are present in CD, but not in UC. Therefore, when they are found in tissue samples taken from an inflamed section of the digestive tract, they are a good indicator that CD is the correct diagnosis.
In UC, the mucus lining of the large intestine is ulcerated. These ulcers do not extend beyond this inner lining. In CD, the ulceration is deeper and may extend into all the layers of the bowel wall.
Complications
In CD, strictures, fissures, and fistulas are not uncommon complications. These conditions are less frequently found in cases of UC.Smoking
One of the more confounding aspects of IBD is its interaction with cigarette smoking or tobacco. Smoking is associated with a worse disease course in CD patients and may increase the risk of relapses and surgery. For some people with UC, smoking has a protective effect, though smoking is NOT recommended due to its significant health risks. UC is often called a "disease of non-smokers."Treatment
Medical treatment
In many cases, the drugs used to treat CD and UC are similar. The mainstays of treatment, 5-ASA medications and corticosteroids, are used to treat both conditions. However, there are some medications that have only proved effective in treating one form of IBD or the other. For instance, infliximab (Remicade) is currently only used to treat CD, although it is under study for use in UC.
Surgical treatment
For patients with CD, surgery to remove diseased sections of bowel may provide some relief from symptoms, but the disease tends to recur. Because the inflammation only occurs in the large intestine in UC, the removal of that organ (called a colectomy) is considered a "cure." Removing only part of the colon is not usually done with UC patients, as the disease will recur in the portion of the colon that is left.
After a colectomy, a UC patient may have an ileostomy or one of several types of internal pouches created from healthy small intestine. Internal pouches are not created in CD patients who must undergo colectomy, because the CD may occur in the pouch. If the pouch became inflamed it would have to be removed in another surgery.
