Overview of Inflammatory Bowel Disease (IBD)
The two primary types of inflammatory bowel disease (IBD) are
These two diseases have many similarities and sometimes are difficult to distinguish from each other. However, there are several differences. For example, Crohn disease can affect almost any part of the digestive tract, whereas ulcerative colitis almost always affects only the large intestine.
The cause of inflammatory bowel disease is not known, but evidence suggests that normal intestinal bacteria trigger an abnormal immune reaction in people with a genetic predisposition.
Inflammatory bowel disease affects people of all ages but usually begins before age 30, typically from age 14 to 24. A few people have their first attack between the ages of 50 and 70. IBD is most common among people of Northern European and Anglo-Saxon descent and is 2 to 4 times more common among Ashkenazi Jews than non-Jewish whites who live in the same region. Both sexes are equally affected. First-degree relatives (mother, father, sister, or brother) of people with IBD have a 4- to 20-fold increased risk of developing IBD. The tendency to run in families is much higher in Crohn disease than ulcerative colitis.
The symptoms of inflammatory bowel disease vary depending on which part of the intestine is affected and whether the person has Crohn disease or ulcerative colitis. People with Crohn disease usually have chronic diarrhea and abdominal pain. People with ulcerative colitis usually have intermittent episodes of abdominal pain and bloody diarrhea. In both diseases, people with longstanding diarrhea may lose weight and become undernourished.
Sometimes IBD can affect other parts of the body such as the joints, eyes, mouth, liver, gallbladder, and skin. IBD also increases the risk of cancer in areas of the intestine that are affected.
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 does several tests.
Stool samples are analyzed for evidence of a bacterial or parasitic infection (acquired during travel, for example), including a type of bacterial infection (Clostridium difficile infection) that can result from antibiotic use.
Tissue samples may be taken from the lining of the rectum during sigmoidoscopy (an examination of the sigmoid colon using a viewing tube) and examined microscopically for evidence of other causes of colon inflammation (colitis). This removal and examination of tissue is called a biopsy.
Doctors also consider other disorders that cause similar abdominal symptoms such as irritable bowel syndrome, ischemic colitis (which occurs more often in people older than 50), malabsorption syndromes, including celiac disease, and certain gynecologic disorders in women. The doctor may do imaging studies, such as x-rays, computed tomography (CT), or magnetic resonance imaging (MRI) of the abdomen to rule out other disorders. The doctor may do video capsule endoscopy to evaluate the intestines of people who have Crohn disease.
Although there is no cure for IBD, many drugs (see Table: Drugs That Reduce Bowel Inflammation Caused by Crohn Disease and see Table: Drugs That Reduce Bowel Inflammation Caused by Ulcerative Colitis), including aminosalicylates, corticosteroids, immunomodulating drugs, biologic agents, and antibiotics, can help reduce inflammation and relieve the symptoms of IBD.
People with very severe disease sometimes need surgery.
Most people and their families are interested in diet and stress management. Although some people claim that certain diets have helped improve their IBD, including one with rigid carbohydrate restrictions, diets have not been shown to be effective in clinical trials. Doctors sometimes recommend stress management techniques to help people deal with the stress of having a chronic disease.
IBD puts people at increased risk of developing certain infections and disorders because of their underlying disease, poor nutrition, or use of immunomodulating drugs. Vaccinations and diagnostic tests and screenings can help lessen the risk.
The influenza vaccine is needed every year to help protect against the flu. The pneumococcal vaccine helps protect against bacterial infections caused by Streptococcus pneumoniae. People who are over age 50 who are not taking biologic agents should consider receiving the herpes zoster vaccine (to help protect against shingles). People who are going to start taking immunomodulating drugs and who have not been exposed to the varicella virus should receive the varicella vaccine (to protect against chickenpox) before starting immunomodulating drugs. People should also receive routine tetanus-diphtheria, hepatitis A, hepatitis B, and human papillomavirus vaccines if appropriate.
Women who have IBD and who are not taking immunomodulating drugs should have cervical cancer screening with a Papanicolaou (Pap) test every 3 years. Women who have IBD and who are taking immunomodulating drugs should have a Pap test every year.
People at risk of decreased bone density (osteoporosis) should have a dual-energy x-ray absorptiometry (DXA) scan.