Diagnosing Crohn's disease
A doctor will make a diagnosis of Crohn's disease based on a person's symptoms and medical history, as well as with the results of some tests.
There is no single medical test for Crohn’s disease, and because it has symptoms in common with other conditions, these may also need to be ruled out.
Physical examination and medical history
Your doctor will begin by gathering information about your health history and conducting a physical examination. Findings that may indicate further tests are needed include:
- Diarrhoea, which may be bloody
- Family history of Crohn's disease
- Pain and tenderness in the abdomen
Your doctor may request laboratory tests in order to look for any problems that might be linked to Crohn's disease. These tests check for signs of infection, inflammation, internal bleeding, and low levels of substances such as iron, protein, or minerals. Lab tests may include:
- Blood protein levels
- Blood sedimentation rates
- Body mineral levels
- Red blood cell counts
- Stool samples to check for blood or infectious microbes
- White blood cell counts
Imaging studies and endoscopy
Crohn's disease may appear anywhere along the gastrointestinal tract from the mouth to the rectum. X-rays and other images can help identify the severity and location of Crohn's disease. These studies may include the following:
Barium X-rays and other X-rays
A barium X-ray can show where and how severe Crohn's disease is. It is especially helpful for finding any problems in parts of the small intestine that can't be easily viewed by other techniques.
A chalky fluid containing barium is given by mouth or through the rectum. When barium fluid is given by mouth, it is called an upper GI series, or barium meal. When barium fluid is placed in the rectum, it is called a barium enema. The barium fluid flows through the intestines, appearing white on X-ray film. This makes it easier to view problem areas. On a barium X-ray, your doctor may be able to see ulcers, narrowed areas of the intestine, or other problems.
If barium X-rays show some sign of disease, your doctor may request other X-rays or imaging studies. These X-rays can help identify exactly how much of your digestive tract is affected by Crohn's disease.
CT scanning uses computer-aided X-ray techniques to produce more detailed images of the abdomen and pelvis than can be seen in traditional X-rays. CT scans can help detect abscesses that might not show up on other X-rays. Abscesses are small pockets of infection.
Colonoscopy or sigmoidoscopy
Colonoscopy and sigmoidoscopy allow the doctor to directly view the large intestine, which is the lower part of the digestive tract. These techniques can often provide the most accurate information about the intestines. They may be better at detecting small ulcers or inflammation than other techniques. They can be used to assess the severity of any inflammation. Colonoscopy is the most important tool in diagnosing Crohn's disease.
During these procedures, a flexible viewing tube is placed through the anus into the large intestine. An image of the inside of the intestine is often projected onto a video monitor. A sigmoidoscopy involves examining the lowest part of the large intestine. A colonoscopy can provide a view of all of the large intestine. In either case, the doctor can directly view the colon to check for signs of ulcers, inflammation, or bleeding. The doctor can also take small samples of tissue to examine under a microscope. This helps determine whether the tissue shows signs of Crohn's disease or other problems.