Colonoscopy Frequently Asked Questions

What, exactly, is a colonoscopy?

In a colonoscopy, your physician visually examines the inner lining of your large intestine, also called a colon. This is done with a thin, flexible tube that has a tiny camera on the end. The tube is gently inserted into the large intestine through the rectum and guided into the intestine to see its entire length.

Can colon cancer be prevented?

Yes, the removal of polyps from your large intestine can actually prevent colon cancer. Colon cancer is the most preventable form of cancer.

People are often surprised to learn that colon cancer is also one of most common cancers in the United States. In the U.S., it is the second leading cause of cancer deaths in men and women.

What is the difference between having a colonoscopy and having a sigmoidoscopy?

In a sigmoidoscopy, the physician sees only half of the patient’s colon. If the physician finds a polyp during a sigmoidoscopy, he or she will most likely schedule a colonoscopy so that the entire colon can be examined. Sigmoidoscopy is not as accurate as a colonoscopy.

What is the difference between having a colonoscopy and having a virtual colonoscopy?

If your physician finds a polyp when he or she is doing your colonoscopy, it can most often be removed at the time. A virtual colonoscopy is an imaging test that uses x-rays and computers. If a polyp or other abnormality is discovered in a virtual colonoscopy, the patient needs to return for another procedure, a colonoscopy, so that the polyp or polyps can be removed.

Why should I have a colonoscopy rather than a sigmoidoscopy, virtual colonoscopy or Cologuard test?

Colonoscopy is the only test presently that is proven to detect and prevent colon cancer. There are alternatives for individuals who do not wish to undergo colonoscopy. Any colon cancer screening is better than none.

What kind of doctor should perform my colonoscopy?

Gastroenterologists are highly trained specialists in performing colonoscopies. Colonoscopies performed by a gastroenterologist had a 65% reduction in risk for colorectal cancer mortality (death), compared with 57% when performed by a primary care provider and 45% when performed by a surgeon. (These results are from a study reported in the New England Journal of Medicine “Journal Watch.”)

Will I be awake during my colonoscopy?

Most patients choose to receive a sedative that makes them feel relaxed and drowsy. They are very comfortable and do not have much recollection of their colonoscopy.

Occasionally, patients prefer not to receive medications and will be awake during their procedure.

Will it hurt?

Most patients do not experience pain. Some patients may feel some discomfort such as cramping, but a common patient comment is “My colonoscopy was very easy; it was the prep that was difficult!”

Will my colonoscopy be done in a private room?

Yes – absolutely.

What is a polyp?

A polyp is an abnormal growth on the wall of your colon, or large intestine. Some are pre-cancerous. Polyps do not cause symptoms. That’s one reason why colonoscopy is so important. Removing polyps can prevent colon cancer. It’s important to know that colon cancer can actually be prevented.

What happens if the doctor finds a polyp during my colonoscopy?

Your gastroenterologist will remove any polyps he or she finds during the examination of your colon at the same time as the examination.

How do I prepare for my colonoscopy?

Generally, preparation involves a diet of clear liquids for about a day, and medications to cause diarrhea. Your gastroenterologist will give you specific guidelines about preparation.

What if my preparation for my colonoscopy isn’t thorough?

The goal of your prep is to have only clear/yellowish fluids in your large intestine so that your gastroenterologist can see the walls of your colon.

Prep Stool Chart

Fecal matter in your colon makes it harder to examine and therefore harder to find any polyps. If your preparation doesn’t seem to be working, call us.

good prep

Good colonoscopy prep


bad prep

Poor colonoscopy prep

Can I go to work following my colonoscopy?

Usually patients prefer to go home and rest. If you do not have drugs administered, you can generally return to work. However, all patients need to have someone present at Portland Gastroenterology to accompany them when they leave, and to be the driver.

What are the common myths about Colon Cancer?

According to the American Cancer Society:

  1. Colorectal cancer is a man’s disease. Not true.
  2. Colorectal cancer cannot be prevented. Not true.
  3. It’s better not to get tested for colorectal cancer because it’s deadly anyway. Not true.

Click here to learn more from the American Cancer Society.