3/6/2013 10:00:00 AM Dr. K for March 6, 2013 Colonoscopy prep is unpleasant but could save your life
DEAR DOCTOR K: I'm scheduled to have my first colonoscopy. My friends tell me the preparation is worse than the procedure. What am I in for?
DEAR READER: From my long experience as a doctor -- and as a patient -- I think your friends have it right.
The large intestine (colon) is a long tube through which digested material passes. In a colonoscopy, a flexible tube with a light and camera at the end is placed inside the colon. What the doctor is looking for are abnormalities in the circular inner wall of the colon, including tumors, bleeding and inflammation.
Colon cancer usually starts in small polyps on the inner surface of the colon. So with one test, these precancerous polyps can be spotted and removed with a colonoscope. (I've put an illustration of this on my website, AskDoctorK.com.)
The doctor can't see the wall when there is feces inside the colon. So before the colonoscopy is performed, the colon needs to be cleared out. That's what the bowel preparation -- or, simply, "the prep" -- is for. The prep typically involves drinking about a gallon of a foul-tasting solution that provokes diarrhea, so you spend a lot of time near, and on, the toilet. Remember "near." You don't want to be too far away.
The day before the colonoscopy, you'll have to stop eating solid foods. You'll switch over to a clear liquid diet.
The traditional bowel preps are polyethylene glycol (PEG) solutions. They wash fecal matter out of the colon by flooding the gut with fluid. The problem is the amount you need to drink for a good bowel cleansing. That would be a cup every 10 minutes until the gallon is gone or until your stool is watery and clear, whichever comes first.
If you take laxative pills before you drink the PEG solution, the amount of solution you need to drink can be cut in half.
A few years ago, guidelines changed to make the prep a little easier. Patients can now drink half of the liquid prep the day before the examination and the other half the day it's scheduled -- instead of all of it the day before.
Once you're cleaned out, the colonoscopy is performed. Most often, you're given a sedative just before the procedure begins. That leaves you and your colon very relaxed. You may wander in and out of dreamland. You feel things, but experiencing pain is unusual.
The sedative dims your memory of what happened. I can remember the names of many of my high school friends, but can't tell you much about the colonoscopy I had last year. On the other hand, I could tell you a lot about the prep I had last year.
Colonoscopy is the best defense against colorectal cancer. So while the prep is unpleasant, it's a small price to pay for a procedure that may save your life.
(Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.)