What colonoscopy prep is best for you?

No one ever looks forward to the dreaded clean-out before a colonoscopy. Whether your gastroenterologist recommends a powdered or pill form prep, it’s safe to say you will be drinking a lot of fluid.

One prep that Falmouth gastroenterologist Joseph Cobb, MD, recommends is Miralax.

“I go with Miralax unless the patient requests something different,” he said. “Miralax contains polyethylene glycol, which is the same ingredient for Go-Lytely and Nu-Lytely. It is a huge molecule that is not absorbable. It stays in the gut, draws water into the gut and does not get drawn into the blood stream, which makes its use safe for patients with any medical condition. The only concern for patients with kidney problems is dehydration so that’s why we harp on people to stay hydrated the day before the colonoscopy.”

Polyethylene glycol causes water to be retained with stool, which increases the number of bowel movements and makes stool softer, so it is easier to pass, according to Medline Plus.

Dr. Cobb recommends mixing the Miralax with Gatorade, which contains electrolytes and comes in a variety of flavors.

Sutab is a prep that has received some press recently. It is an oral sulfate-based pill that is taken in two doses consisting of 12 tablets each followed by 1 ½ quarts of water. The first dose is taken the night before your colonoscopy and the second dose the morning of your colonoscopy. It was approved by the Federal Drug Administration (FDA) in 2020 and the first tablet to receive approval in 10 years as an alternative to liquid preparations according to the Colorectal Cancer Alliance.

“Sutab is a fine prep and people like it because they believe they are taking less fluid,” said Dr. Cobb. “In essence, they are drinking 96 ounces of water if they take the prep as directed. The Gatorade/Miralax combination is 64 ounces. Either way you have to drink a lot of liquid.”

Prep and Diet Tips

Dr. Cobb recommends the following for colonoscopy prep:

• Be sure to tell your gastroenterologist if you prefer a specific prep.
• When drinking the prep, divide the dose and drink slowly.
• You can use a straw, which may help you bypass the taste of the prep.
• The prep may be more palatable if you drink it cold.
• Eat a low residue diet for five to seven days prior to taking the prep.
• Drink a lot of fluids the day before the colonoscopy to prevent dehydration.

The preps are also used for some surgical procedures, such as colon surgery.

“The gastroenterologist is looking for polyps and growths when they do a colonoscopy so they want to have a really good prep that allows good visualization of the colon,” said Peter Hopewood, MD, a Falmouth Hospital surgeon with Cape Cod Surgeons. “We use Miralax and Dulcolax tabs for a prep. Our goal is to get rid of the fecal load to minimize the risk of infection in bowel surgery.”

Other Options for Colorectal Screening

Dr. Cobb and Dr. Hopewood agree that the Cologuard and FIT tests are fine to use, especially if you are hesitant to have a colonoscopy.

Cologuard is a test that requires a sample of stool, which you collect at home, place in a container, and mail to the lab. The lab checks for atypical DNA or traces of blood that may suggest precancerous polyps of colorectal cancer. The test is repeated every three years. Its accuracy is limited and 13 percent of the time it indicates a patient may have cancer when they don’t, according to Harvard Health Publishing.

“If it’s Cologuard or nothing, by all means, do a Cologuard,” said Dr. Cobb. “However, we do find more false positives in the older population. There is a 30 percent false positive rate after the age of 70.”

Fecal immunochemical test (FIT) is another test you do at home. You collect your stool in the privacy of your home and mail it to the lab and you do the test annually. It has a false positive rate of about 5 percent according to Harvard Health Publishing. It can rule out colorectal cancer with a 79 percent accuracy. If it is positive, then a colonoscopy will be needed.

FIT is a good lab test and the only test that has shown a survival benefit with all the studies, said Dr. Cobb. “The only concern is polyps can bleed intermittently and if you happen to test on a day they aren’t bleeding, then that’s a worry.”

People like the FIT or Cologuard tests because they can be done at home and there is no risk, according to Dr. Hopewood. “However, colonoscopy remains the gold standard for finding small polyps and pre-malignant polyps and removing them.”

Dr. Cobb and Dr. Hopewood both agree that any colon screening is better than no colon screening.