Gastric bypass surgery does not significantly affect the colon, so it should not create unique safety issues for procedures that involve the colon.

In general, I am skeptical about the usefulness of bowel-cleansing products. Laxatives (medicines or herbs that stimulate the bowel to pass stool) and rinses for the bowel (by mouth or by enema) can be useful for treating symptoms of constipation. However, I do not recommend them to people who don't have constipation because they can cause side effects.

Laxatives and rinses can alter the concentration of electrolytes in your bloodstream, a problem that is occasionally dangerous.

Also, laxatives can cause cramping and diarrhea. And if used frequently, they can damage the nerves in the bowel lining. This nerve damage can result in a tendency to be constipated between laxative doses.

There is wide variation in normal bowel frequency. If you have at least three stools each week, your bowel pattern is frequent enough, according to most experts. It is not important to empty your colon of stool before you feel ready to have a bowel movement. The healthiest way to encourage regular bowel movements is to eat a diet that is high in fruits, vegetables, and whole grain foods. By doing so you will optimize your nutrition, reduce your risk of colon cancer, and improve your digestive health.