Crohn's disease cannot be diagnosed using a single test, so doctors often use a variety of methods to rule out other issues and confirm the diagnosis. A medical history and physical examination is typically done to determine if the patient has risk factors and symptoms indicative of Crohn's. Blood and stool samples may be taken to look for signs of the disease. Other Crohn's tests include procedures that create images of the gastrointestinal tract such as X-rays, MRIs, and CT scans, and those that involve inserting viewing devices directly into the intestine such as colonoscopy, video endoscopy, and sigmoidoscopy.
One of the first Crohn's tests most doctors will start with is a basic physical examination. He or she will review the patient's medical history and family history to look for any risk factors. The patient should also tell the doctor about any symptoms that could indicate Crohn's, such as ongoing diarrhea, abdominal pain, or blood in his or her stool. After this initial examination, the doctor will then typically order additional tests if he or she think Crohn's is a possibility.
The doctor may order certain types of lab analyses as part of a course of Crohn's tests. Stool samples can be used to determine if the patient has intestinal bleeding or signs of infection in the intestines. Blood tests can be used to look for signs like changes in red or white cell counts, abnormal fat or protein levels, and anemia. In some cases, a biopsy of intestinal tissue may also be studied.
Crohn's tests that provide imaging from the intestines and other portions of the GI tract are often useful to determine where the disease is causing issues and how severe they are. X-rays, particularly those incorporating barium, can clearly show the location of damaged areas. CT scans can help locate smaller ulcers and abscesses. MRIs may also be used to provide a detailed view of the abdomen.
Internal exploration of the intestines is probably the most effective of the various Crohn's tests available. Both colonoscopies and sigmoidoscopies involve inserting a flexible tube through the anus into the intestines, where the doctor can then use it to look for inflammation, ulcers, or other signs of the disease. A video endoscopy can be performed using an endoscope equipped with a camera in a similar fashion, or the camera may be swallowed as a pill so it passes through the entire GI tract, transmitting images as it goes.