McClary: What you need to know about colonoscopy and colorectal cancer screening


Colon cancer and rectal cancer; the words create fear in some, disgust in others. The colon and rectum are parts of our bodies we keep private, hidden and secret. Though none of us want to show that part of our body to others, getting a colonoscopy to screen for colon cancer can make the difference between our life or death.

That’s why it’s important to share this information during March, national Colorectal Cancer Awareness Month.

The colon and rectum are the lowest part of our intestine, also called the large intestine. The rectum is the name for the last part of the colon just before the anus. The inside lining of this muscular, six-foot long tube can give rise to growths called polyps and some polyps can grow into colon cancer. Polyps and colon cancers rarely create symptoms such as pain or bleeding — so we call colon polyps and cancers “silent.”

Our colon is like a black box; we have no idea what can be growing inside. Through colonoscopy, doctors can inspect the inside lining of the colon, remove polyps that might be growing inside of you and prevent those from becoming colon cancer.

Prior to colonoscopy, every patient must drink a preparation that washes out the inside of the colon, thus at the time of colonoscopy the inside of the colon is clean and pink. We have many old-style colon preparations as well as several new options, including small-volume preparations and even a pill preparation.

For the colonoscopy procedure itself, it is done with the utmost privacy in a procedure room with experienced nurses and doctors present to watch you and ensure your safety. Every patient is put into a deep sedation by a board-certified anesthesiologist or anesthetist for the duration of the procedure, so you will have no memory of the procedure or any pain.

The procedure takes about 20 minutes to complete. Afterwards, people wake up feeling mildly gaseous, but otherwise are pain free. You must have another adult accompany you home as you are considered impaired for the rest of the day after the anesthesia.

Usually, colon cancer doesn’t affect us until we are older; however, we are seeing more case in younger patients these days. Any patient at any age who has new rectal bleeding, changes in the way their bowels function, new constipation, narrowing of their bowel movements, or other unexpected bowel changes should consider having a colonoscopy to be certain these changes aren’t caused by cancer or polyps.

In general, the risk of developing colon polyps and cancer increases as we get older, so formal guidelines recommend that patients have a screening colonoscopy around the age of 50 and every ten years thereafter until age 75.

If a patient has a first-degree relative — such as a parent, sibling, or child — with colon cancer or major colon polyps, the patient should undergo colonoscopy by age 40 or ten years younger than the age at which the relative was diagnosed, whichever comes first, and repeat the procedure every 5 years.

Screening colonoscopy is an important tool for diagnosing colon cancer. If you have questions, please speak with your physician.

Editor's note: Dr. Debora McClary is a colorectal surgeon on the medical staff at that Abrazo Arrowhead Campus in Glendale. Visit