You need to clean out your colon before the procedure so the doctor can see your colon. This depends on which "colon prep" your doctor recommends.

To clean out your colon, you'll do a "colon prep" before the test. This means you stop eating solid foods and drink only clear liquids. You can have water, tea, coffee, clear juices, clear broths, flavored ice pops, and gelatin (such as Jell-O). Do not drink anything red or purple.

The day or night before the procedure, you drink a large amount of a special liquid. This causes loose, frequent stools. You will go to the bathroom a lot. Your doctor may have you drink part of the liquid the evening before and the rest on the day of the test. It's very important to drink all of the liquid. If you have problems drinking it, call your doctor.

Arrange to have someone take you home after the test.

A colonoscopy may be done in a doctor's office, clinic, or a hospital.

During the test, you may get a pain medicine and a sedative put in a vein in your arm (I.V.). These medicines help you relax and feel sleepy during the test. You may not remember much about the test.

Before the test

You will need to take off most of your clothes. You will be given a gown to wear during the test.

You may lie on your left side with your knees pulled up to your belly. Because you will be given medicine during the colonoscopy, you probably won't remember having the test when you wake up.

Next, the doctor will insert a thin, flexible colonoscope in your anus and move it slowly through the rectum and into your colon. Air will be used to inflate your colon so the doctor can see the lining of the colon on a monitor.

During the test

Your doctor will look at the whole length of your colon as the scope is gently moved in and then out of your colon. You may be asked to change your position during the test.

The doctor may also collect tissue samples (biopsy) or take out growths. Usually, people don't feel anything if a biopsy is done or if polyps are taken out.

The scope is slowly pulled out of your anus, and the air escapes. Your anal area will be cleaned with tissues. If you are having cramps, passing gas may help relieve them.

After the test

After the test, you'll stay at the clinic until you wake up and then have a brief visit from your doctor. Then you'll be allowed to leave with the person who will drive you home.

After a colonoscopy, you'll stay at the clinic until you wake up. Then you can go home. But you'll need to arrange for a ride. Your doctor will tell you when you can eat and do your other usual activities.

Your doctor will talk to you about when you'll need your next colonoscopy. Your doctor can help you decide how often you need to be checked. This will depend on the results of your test and your risk for colorectal cancer.

After the test, you may be bloated or have gas pains. You may need to pass gas. If a biopsy was done or a polyp was removed, you may have streaks of blood in your stool (feces) for a few days. Problems such as heavy rectal bleeding may not occur until several weeks after the test. This isn't common. But it can happen after polyps are removed.