Q. Wouldn’t having an enema prior to a colonoscopy virtually wipe out one’s internal microbiome?

A. Preparing for a colonoscopy requires clearing the bowel with fasting, a laxative drink and, in some cases, an enema. While such preparation can alter the microbiome, the rich array of microbes that are present in the gut, research suggests that the microbiome bounces back in about two to four weeks.

“It does significantly shift the community for a short period of time, but as far as we know doesn’t have any long-term consequences,” said Dr. Ilseung Cho, a gastroenterologist and assistant professor of medicine at NYU Langone Medical Center.

Even an enema won’t clear out all the bacteria from the colon, said Dr. Ari Grinspan, a gastroenterologist at the Icahn School of Medicine at Mount Sinai. People’s microbiomes tend to be very stable after the age of about 3.

“If you go to Thailand and eat interesting food, or get a bug of some kind, your microbiome will change, but in most cases, it will go back to its normal state afterwards,” Dr. Grinspan said.