Diagnosis of Inflammatory Bowel Disease
To diagnose inflammatory bowel disease, physicians usually take a medical and family history and perform a physical examination and diagnostic tests (e.g., laboratory tests, imaging tests). Laboratory tests that may be used include blood tests and stool samples.
Blood tests can detect anemia (low red blood cell count), which may indicate GI bleeding, and also can detect signs of inflammation (e.g., high white blood cell count). Stool samples involve examining fecal matter for signs of GI inflammation (e.g., pus [infectious material], blood) and bacteria, viruses, or parasites.
The fecal occult blood test (FOBT) can be used to detect hidden (occult) bleeding in the digestive system. In this test, a chemical reaction is used to detect the presence of blood in a series of small stool samples.
Endoscopic procedures and imaging tests often are performed to help diagnose inflammatory bowel disease. These tests include upper GI series, lower GI series (barium enema), colonoscopy, flexible sigmoidoscopy, and CT scan.
An upper GI series can help detect IBD that affects the small intestine. Prior to this procedure, the patient drinks an oral contrast solution (barium), which helps provide clearer images. Then, a series of x-rays are taken.
In endoscopy, the patient drinks an oral contrast solution and a device containing a tiny light and camera (called an endoscope) is passed through the throat and into the esophagus, stomach, and small intestine. This test allows the physician to examine the digestive tract and detect inflammation.
A lower GI series, also called barium enema, is similar to upper GI series, but is used to examine the colon and rectum (i.e., the larger intestine). Prior to undergoing this test, the colon must be completely empty. Patients often are instructed to follow a diet of clear liquids only the day before the procedure, and to avoid eating anything after midnight on the day of the test. A laxative or cleansing enema also may be administered.
During the procedure, barium is introduced into the colon through a small tube inserted into the rectum and a series of x-rays are taken to detect inflammation. The contrast solution, which coats the lining of the colon, helps to provide clearer x-ray images.
Colonoscopy, also called total colonoscopy, allows the physician to examine the colon using a thin, hollow, lighted tube with a tiny video camera attached (called a colonoscope). The colon also must be completely empty before the patient undergoes this procedure.
During this test, the colonoscope is inserted into the rectum and is passed through the colon, allowing the physician to examine the colorectal lining directly. Flexible sigmoidoscopy, which is similar to colonoscopy, allows the physician to examine the rectum and lower part of the colon (i.e., sigmoid colon) using a sigmoidoscope.
Computed tomography (CT) scan, also called computerized axial tomography (CAT) scan, may be used to help diagnose some types of IBD. In this procedure, x-rays of the GI tract are taken from many different angles and processed through a computer to produce three-dimensional (3-D) images. In some cases, the patient drinks an oral contrast solution prior to CT scan to provide clearer images.