Questions and answers about colonoscopies

Few health care interventions can reduce the risk of dying from a disease by more than 50 percent.

Few health care interventions can reduce the risk of dying from a disease by more than 50 percent.

While a colonoscopy might be uncomfortable to talk about, people should pay attention to a new study in the current issue of the New England Journal of Medicine. Researchers found the death rate from colorectal cancer was reduced by 53 percent in people who had a colonoscopy that detected and removed precancerous growths, called adenomatous polyps.

As a patient, I’d like those odds of survival, even if it means slight discomfort.

Below are some common questions I hear about colonoscopies, including the usual concerns about preparation and the procedure itself.

What message should I take away from this new study?

This study is tremendously important, and the large sample size and long follow up time lend a great deal of credence to their conclusions. The study shows, quite emphatically, that patients who have precancerous adenomatous polyps identified and removed at colonoscopy are less likely to die from colorectal cancer than the general population. The difference was quite impressive, as well – they were 47% as likely to die from colon cancer than the average person who may have had a polyp, but didn’t have a colonoscopy so it could be identified and removed.

What do I have to do to prepare for a colonoscopy?

A thorough bowel preparation is essential to getting a good look at the colon wall, so even the smallest polyps can be identified and removed. People who don’t finish their prep because it doesn’t taste good, because of cramps, or because of the volume of fluid to drink are really short-changing themselves. The effects of a bowel prep are something that I think everyone has experienced at some point or another – heavy diarrhea. It’s not pleasant, but it’s manageable and potentially as infrequent as once in 10 years if the colonoscopy is normal.

What will I feel during a colonoscopy?

Colonoscopies are performed with IV sedation and pain medications. These are given at the start of and during the procedure to keep the patient comfortable. Because air is introduced into the colon in order to see, some bloating and mild cramping during the procedure is to be expected. One of the effects of the sedation is also some amnesia, so most patients don’t even remember how they felt during the colonoscopy once the test is over. The vast majority of patients do great.

How often do you find polyps?

Most studies show that polyps are detected slightly more than 20 percent of the time. Not each and every polyp removed has the potential to turn into a colon or rectal cancer, but with the naked eye we can’t really tell which ones those are. That’s why we remove them and have the pathologist check under the microscope.

Are there alternatives to colonoscopy that are equally effective?

Colonoscopy is considered the “gold standard,” but screening through means other than colonoscopy is better than no screening at all. Other screening tests for colorectal cancer exist and are recognized as satisfactory by multiple organizations. These include air contrast barium enema and CT colonography. Both of these tests are performed by radiologists and are “noninvasive,” or more accurately less invasive. For both, patients still undergo a bowel prep, and in each, the colon gets filled with air to allow evaluation of the wall. A main difference in terms of comfort is that sedation is not administered when the colon gets insufflated. The other main disadvantage is that these tests are purely diagnostic, and not therapeutic – if a polyp is identified, it can’t be removed by X-ray. A colonoscopy would then have to be performed in order to identify the lesion and attempt removal. If no abnormalities were found on barium enema or CT colonography, however, then the risks of sedation and the more invasive procedure (colonoscopy) could be avoided.

Some patients are concerned about the possibility of complications from colonoscopies, but fortunately the rate of serious complications is very low.

If you need a reminder of the importance of a colonoscopy, consider this: Each year, more than 140,000 people are diagnosed with colon or rectal cancer in the United States, and 50,000 people die. Age is the most important risk factor for the disease, so even people who lead a healthy lifestyle can still develop polyps and cancer. Both men and women are equally affected. Screening should begin at age 50 – or earlier if you have other risk factors.