How safe is colonoscopy?

Colonoscopy is widely used to screen people for colon cancer and to monitor those who have had a polyp (pre-cancerous growth) or tumor removed. After inserting a thin, flexible viewing tube into the anus and carefully moving it up through the colon, a doctor examines the lining of the colon and rectum. If a polyp is found, it can be removed using a device at the tip of the scope. Although the procedure is only minimally invasive, it’s not without risk.

Looking at the numbers

To find out how frequently complications occur, a team of researchers reviewed the records of more than 16,000 people, 40 or older, who had undergone colonoscopy in a community setting. Most of the procedures (96%) were performed by gastroenterologists (doctors specializing in diseases of the gastrointestinal tract); 80% of the doctors did at least 150 colonoscopies per year.

Bleeding and perforation

The researchers examined the participants’ medical records for 30 days after their procedure to identify hos-pitalizations that may have been due to procedure-related complications. They found 82 serious complications—95% of which occurred in instances where a biopsy (tissue sample) was taken or more than one polyp was removed. In 53 cases, bleeding was the most common complication. The next-most-common problem was perforation (puncture) of the colon, in 15 cases. One person died as a result of a colonoscopy-related complication.

When no polyps were removed or biopsies done, the rate of serious complications was less than 1 in 1,000 colonos-copies. Considering their findings, the researchers noted, doctors should inform people about the possibility of delayed bleeding. And, follow-up procedures should be in place to monitor this possibility.

Taking the time to do it right

Another important consideration in colonoscopy is the thor-oughness with which the procedure is performed. A separate study found that doctors who take their time withdrawing the scope after it has been inserted up through the colon gener-ally do a better job of detecting abnormalities. Withdrawal is the phase of the procedure when the doctor should carefully examine the colon lining, for example looking behind folds and washing away bits of stool that might obscure a polyp.

From Annals of Internal Medicine and The New England Journal of Medicine