How to Prepare for a Colonoscopy
If you're going to have a colonoscopy, it's important to prepare for it correctly.
A colonoscopy is an invasive procedure in which a physician places a long, flexible tube outfitted with a small video camera into the rectum. This allows the doctor to view the entire colon and look for abnormalities or changes that could be warning signs for colorectal cancer. Physicians typically perform this exam while the patient is under moderate or conscious sedation. Among many experts such as gastroenterologists and colorectal surgeons, a colonoscopy is widely considered to be the best and most reliable way to screen for colon cancer.
"A colonoscopy is the best tool to screen for colorectal cancer as the procedure lets a doctor examine the large intestine for polyps (growths inside your colon that can turn into cancer) or cancer and evaluate symptoms like abdominal pain and rectal bleeding," says Dr. Carol A. Burke, a gastroenterologist and director of the Center for Colon Polyp and Cancer Prevention at Cleveland Clinic.
During the exam, doctors can detect and remove polyps or sample tissue to help diagnose other colon diseases. "Removing polyps during a colonoscopy decreases the risk of colorectal cancer," she says.
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Preparing for a colonoscopy is important because the patient's colon should be as clean as possible, to give the examining physician the best opportunity to spot and remove any potentially cancerous polyps and tissue, says Dr. Mohammad Abbass, a colorectal surgeon at Northwestern Memorial Hospital.
"If the colon lining is not clear of solid and liquid, bowel residue can cover polyps that can then be missed during the colonoscopy," Burke says.
Here are the steps you need to take to prepare for a colonoscopy:
-- Three days before the procedure, cut down on your consumption of high-fiber foods.
-- Consume a clear liquid diet the day before the colonoscopy.
-- Drink prescription bowel-cleaning liquid the morning of the procedure and the day before.
-- Arrange to have a responsible driver take you home after the procedure once you're discharged.
1. Three days before the procedure, cut down on your consumption of high-fiber foods. Fiber residue can clog the scope for the physician doing the colonoscopy from seeing polyps, Burke says. So, patients should stop eating high-fiber foods beginning three days before the procedure.
High-fiber foods include:
-- Beans.
-- Seeds (including flax, sunflower and quinoa).
-- Nuts.
-- Multi-grain bread.
-- Popcorn.
-- Salads.
-- Vegetables.
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2. Consume a clear liquid diet the day before the colonoscopy. To try to assure your colon is as clean as possible the day of the procedure, you'll need to stick to a clear liquid diet the day before, Abbass says. "That means no food that will prevent us from seeing inside your colon."
Here is what you can consume the day before a colonoscopy:
-- Gelatin.
-- Clear soup.
-- Clear juices.
-- Water.
-- Tea.
-- Coffee without cream or milk.
3. Drink bowel-cleaning liquid the morning of the procedure and the evening before. Years ago, prepping for a colonoscopy entailed drinking a large amount of a foul-tasting bowel-cleansing prescription liquid the afternoon or evening before the procedure.
"Prep is much improved these days," Burke says, which makes the process easier. For one thing, the taste of prescription prep liquids has gotten better. Also, "Liquid bowel-cleansing formulas are more efficient than they used to be, so you don't have to drink nearly as much as you did in the past. These days, lower-volume preps are available -- 3-liter, 2-liter and 10-ounce (options) -- and offer an alternative to the old gallon to 4 liters of laxative solution."
Now, patients typically consume part of the bowel-cleansing solution the afternoon or evening before the colonoscopy, and the rest the morning of the procedure. "The split-dose prep means at least half of the bowel prep is (consumed) on the day of the exam," Burke says. This approach is the international standard for these procedures, she says. There shouldn't be more than four to six hours between the last dose of the prep and the start of the colonoscopy, she adds.
Consuming the bowel-cleansing liquid in a split dose results in "decreased intensity and duration of (bowel movements), less patient inconvenience, improved bowel preparation and increased ... polyp detection rates," according to research published in 2016 in the American Journal of Gastroenterology. Burke is one of the study's co-authors.
Weeks before the scheduled procedure, your physician will typically give you a prescription for a bowel-cleansing liquid. You may have to consume all of the bowel-cleansing liquid by the evening before if your procedure is scheduled for early the next morning. Ask your physician what is the best prep option for you.
4. Arrange to have a responsible driver take you home after the procedure once you are discharged. Because you're recovering from the colonoscopy and the effects of the anesthesia, medical offices will typically require you to have a responsible person -- a friend or a relative -- drive you home after the procedure once you're discharged.
