Conditions with similar symptoms include everything from an upset stomach and lactose intolerance to irrational bowel syndrome (IBS).
There are several tests available today to help determine whether a person has Crohn's disease or one of the copycats.
A barium enema is an x-ray of the colon (large bowel or large intestine) including the rectum. This test is performed in a doctor's office or a hospital's radiology department. The physician will insert an enema tube into the patient's rectum and perform an enema using a special chalky liquid called barium sulfate that coats the large intestine, allowing for a greater contrast between specific areas and providing clearer x-rays.
A doctor who performs either a colonoscopy, endoscopy or sigmoidoscopy may also perform a biopsy if he or she suspects Crohn's disease. During a biopsy, the doctor takes a sample of tissue (mucosa) from the lining of either the colon or small intestine. This sample will then be taken to a lab for examination of the anatomy of the cells (histology) under a microscope. It is an excellent test to determine between different types of inflammation or for detecting cancer or dysplasia (abnormal cells).
A blood test (also known as laboratory testing) is performed to check for several types of abnormalities or imbalances including anemia, which may indicate bleeding somewhere in the intestines. A blood test may also reveal an elevated white blood cell count—a sign there is an inflammation located somewhere in the body.
A breath test isn't used to test for Crohn's disease, but it can identify or discount lactose intolerance as the cause of a person's symptoms. When undigested lactose is metabolized in the colon, bacteria there release hydrogen into the bloodstream which can then be measured by this test.
To perform a colonoscopy, a doctor will insert a long flexible tube linked to a computer monitor into the patient's anus, allowing him or her to examine the lining of the colon (large intestine) for inflammation and/or bleeding.
A CT, or CAT Scan, uses sophisticated x-ray computed tomography technology to generate 3D images of the patients bowels from a series of 2D x-rays. The patient drinks a special dye prior to the procedure to help provide contrast in the images.
An endoscope is a small flexible tube with a small camera mounted on the end. A gastrointestinal endoscopy, unlike a colonoscopy or sigmoidoscopy, may be performed through the mouth as well as the anus, thus allowing for a physician to check for Crohn's of the upper GI tract as well as in the colon.
Another type of endoscopy is called capsule endoscopy. The "capsule" is actually a camera (containing a battery, light and transmitter) which the patient swallows and eventually expels. It is less invasive than the standard endoscopy—however there is a chance the capsule will become lodged requiring emergency surgery.
During an enteroscopy, a spray is used to "freeze" a sedated patient's throat and a scope is passed through her mouth, past the esophagus, through the stomach and into the small intestine (small bowel).
Most Crohn's disease, however, is located beyond the reach of the simplest "push" enteroscopic procedure. Single and double balloon techniques allow doctors to examine more of the bowel but require several hours and heavy sedation to perform. It is rarely used to make a diagnosis of Crohn's disease but may help eliminate other causes.
A form of enteroscopy is sometimes used during a CT scan.
Magnetic Resonance Imaging (MRI)
An MRI is performed in much the same way as a barium enema, however, water replaces the barium. Although it is a more expensive test, the equipment is safer than an x-ray for most patients while providing superior images.
A sigmoidoscopy is similar to a colonoscopy, but it only allows a doctor to examine the lining of the lower part of the colon rather than the entire large intestine. Because of its limits, a sigmoidoscopy may be ineffective to test for Crohn's but may help to either determine or to exclude another condition.
By taking a stool sample, a doctor can test for blood or infection in the intestines.
Upper GI Series
For an upper GI series, the patient drinks barium and x-rays are taken of the small intestine rather than the colon.