What Does A Colonoscopy Actually Detect?

Most people think of a colonoscopy as a test for colon cancer. And indeed, this is one of the primary reasons to get a colonoscopy. It allows doctors to spot cancerous and pre-cancerous growths so they can remove them, hopefully before your condition gets too serious. However, cancer is not the only condition that can be detected in a colonoscopy. Here are three other conditions that this test can reveal.

Inflammatory Bowel Disease

Many people suffer from on-and-off bouts of diarrhea, constipation, or both. In some cases, these bouts of digestive distress can go on for years, either because the patient does not realize their condition is a problem, or because bouts come and go infrequently enough that the doctor does not recognize there is a pattern. This pattern of digestive ailments could be due to irritable bowel disease, or IBS. A colonoscopy can detect visible symptoms of IBS, such as damaged and bleeding intestinal lining. The nature of the lesions detected can also inform doctors just how severe the IBS is, which will guide their treatment approach. Some patients just need to make some dietary changes, and others need steroid medications. Colonoscopy results can help reveal how intense of an approach you need to take.


Diverticulosis is a condition in which the large intestinal lining starts to form pockets. Things like seeds and particles of poorly digested foods can get stuck in these pockets, leading to intense bleeding and pain. A colonoscopy can detect diverticulosis pockets even before the symptoms appear. If your doctor sees these pockets on your colonoscopy images, they will recommend dietary restrictions to prevent you from having flare-ups. Generally, you'll be told to avoid seedy foods, like raspberries and popcorn, and to eat more high-fiber grain products.


Colitis is a general term for inflammation of the colon. It can be caused by an infection, by untreated IBS, or even by an autoimmune disease. A colonoscopy can be used to diagnose colitis, and from there, your doctor can start working on figuring out the cause of the colitis so it can be treated. A colonoscopy is an important first step because it confirms that the issue is actually in the large intestine, and not further up in the digestive tract.

A colonoscopy can be used to detect cancer, but that's not its only purpose. This test may also be ordered if your doctor suspects you might have IBS, colitis, or diverticulosis.