Diagnosis and Testing

After providing medical history, symptoms, blood and stool tests, your health care provider may refer you to see a gastroenterologist for further testing using endoscopic procedures. An endoscopy or colonoscopy is required to make a diagnosis of Crohn's or colitis, and is considered the 'gold-standard' in IBD testing. 

The main types of endoscopic testing includes upper endoscopy and colonoscopy. The type of endoscopy used by your physician may depend on whether you have ulcerative colitis or Crohn’s disease.

Ulcerative colitis affects the colon (large intestine), always involving the rectum and extending upwards from there. Each patient differs in terms of how far up through the colon the colitis extends.

Crohn’s affects the entire digestive tract, including the esophagus, stomach, both the small and large intestines, and/or rectum. There can be normal the areas interspersed with areas that are affected (inflamed). Some people have disease that affects the upper gut, which includes the esophagus, stomach, and early part of the small intestine. 

What is the upper endoscopy used for?

Gastroenterologists will use an upper endoscopy to check for signs of inflammation in the upper GI tract. It is used to make a diagnosis of Crohn's disease. It provides IBD specialists with a direct look at the gastric mucosa of the intestinal tract (a membrane that covers the surface of internal organs and produces a protein that helps food pass through the stomach, and provides a protective layer on top of the lining of the stomach).

The upper endoscopy test cannot be used to check for signs of inflammation in the colon (large bowel) because the tube cannot reach past the upper part of the small intestine. Doctors must use a colonoscopy to make a diagnosis of colitis.

How is the test done?

The procedure includes an endoscope (flexible tube with a small camera and light on one end) that is being fed through the mouth into the upper gut (esophagus, stomach) and small intestine.

The gastroenterologist watches the camera on a nearby monitor as it travels through the upper GI tract, and take pictures of any problematic areas. ​Most endoscopes also have a tool that allows doctors to take fluid or tissue samples from the GI tract to send for laboratory testing.

The upper endoscopy test cannot be used to check for signs of inflammation in the colon (large bowel) because the tube cannot reach past the upper part of the small intestine. Doctors must use a colonoscopy to make a diagnosis of colitis. This is described in more detail below. 

Preparing for the test

The endoscopy is considered an invasive test that may require patients to go under sedation. To prepare for this test, patients cannot eat or drink anything for eight hours before the test. Your specialist may also ask you to avoid taking certain medications on the day of the test. 

If you were sedated or anesthetic, you will need to arrange for transportation from the clinic or hospital back to your home. Talk to your health care provider if you have any concerns. 

What is a colonoscopy used for?

Colonoscopy (also referred to a sigmoidoscopy) can be used to go backwards from the rectum all the way through the large intestine and into the last part of the small intestine. 

Ulcerative colitis can be assessed using colonoscopy. Crohn’s disease can be hard to evaluate using colonoscopy because the small intestine is 22 feet long with many folds.

How is the test done?

A colonoscopy is conducted by inserting a flexible tube with a small camera on one end into the colon to check for areas of inflammation or lesions. 

The gastroenterologist watches the camera on a nearby monitor as it travels through the rectum and colon or large bowel. They will take pictures of any problematic areas use a tool on the tube to take fluid or tissue samples to send for laboratory testing.

Preparing for the test

A colonoscopy is considered an invasive test and bowel preparation is required before the procedure. Different methods are used to empty the contents of the colon. This mainly consists of changes to diet and drinking bowel-cleaning liquids.

In the days leading up to the procedure, try to eat a low-fibre diet with no grains, nuts, seeds, dried fruit, or raw fruits and vegetables. Talk to your health care provider for more information about diet before a colonoscopy. 

Do not eat solid foods for 24 hours prior to the colonoscopy procedure. Your health care provider will advise you to consume only clear liquids like clear broth, Jell-O, popsicles, black coffee or tea, clear juice (apple), or clear sports drinks.

In the afternoon or evening before the colonoscopy, you will need to drink a medical liquid that is prescribed by your health care provider. This liquid will trigger the bowel to start clearing contents and may cause diarrhea. Make sure to be near a bathroom and wear loose clothing after taking the liquid.

Drink lots of clear liquids before, during, and after bowel preparation to avoid dehydration from diarrhea. Don't eat or drink anything two hours before the colonoscopy procedure. 

If you were sedated or put under anesthetic, you will need to arrange for transportation from the clinic or hospital back to your home. Talk to your health care provider for more information. 

Capsule endoscopy is when you swallow a pill that contains a camera, which then travels through your digestive system taking pictures. Physicians do not use capsule endoscopy very much in Crohn’s disease because if there are any areas of narrowing along the digestive tract, the camera could become stuck. However, for some people, this test can be useful. Speak to your health care provider or IBD specialist for more information.