Three Things to Know About Today’s Colonoscopy
Going for a colonoscopy is no one’s favorite outing. But there have been key changes to the procedure and guidelines that spell good news for patients.
“Many people consider colonoscopy a necessary, if not very pleasant, part of life,” says gastroenterologist Benjamin Lebwohl, MD. “However, these recent changes make for an easier prep and more effective cancer prevention.”
A colonoscopy is a common outpatient procedure that examines the colon and rectum for signs of disease, such as cancer. The procedure may also involve removing polyps or tissue for further examination. Although your doctor may order a colonoscopy because you’re having symptoms, the procedure is routinely done to screen for cancer and precancerous polyps in healthy people. During a colonoscopy, the patient often undergoes sedation, while a gastroenterologist (a doctor specializing in digestive diseases) threads a flexible scope through the colon.
Dr. Lebwohl shares the three main ways colonoscopies have improved in recent years.
Colonoscopy Prep Has Changed
To prepare for a colonoscopy, you first have to clean out your colon. If you’ve had a colonoscopy in the past, you may remember limiting your diet a couple of days beforehand, then drinking a prescription laxative that induces diarrhea the night before.
But that preparation has changed: Instead of taking the entire laxative at once, most practices now tell patients to split the drink between the night before and morning of the procedure.
There are two big benefits to this split dose. One is that it makes the experience easier because you’re taking a break. Dr. Lebwohl reassures patients that the morning laxative is unlikely to interfere with travel to the appointment because this second dose induces diarrhea within an hour, so it can be timed with your travel. Although patients may have to wake up early for the second dose, he also points out that the anesthesia given during a colonoscopy often results in feeling well-rested after waking up.
In fact, according to a 2010 paper in Digestive Diseases and Sciences, 85 percent of patients surveyed said they would be willing to get up during the night to take the second dose.
The second benefit of the morning dose is a much better “cleanout,” which helps doctors see the colon, spot polyps, and prevent cancers.
That morning dose is effective even though you haven’t eaten overnight since the first half of the preparation. “There’s a misperception that if you fast, your colon is not exposed to anything that could muck it up,” explains Dr. Lebwohl. “But our digestive organs are always secreting fluids, mucus, and bile. By taking that second dose close to the start of the colonoscopy, you’re rinsing this material out before more can build up, which increases the number of polyps we find, making it more likely that we are preventing cancer from developing.”
The Age to Get Your First Colonoscopy is Now 45
In the past, various guidelines suggested different ages for people to start colonoscopy screenings. Today, all guidelines have agreed on an official (and younger) age: 45.
“In recent years, rates of colon cancer have gone down in people age 50 and up, but they’re rising in younger people,” says Dr. Lebwohl. “The reason for the rise is not fully understood, but it could have to do with an increase in some risk factors, such as being overweight.”
Although 45 is the new starting age for most, some individuals should begin screenings earlier. If you have an above-average risk for colon cancer due to a family history of the disease or because you have other conditions, like Crohn’s disease, talk to your doctor about the right time for you to start screenings.
There Are Other Ways to Screen for Colon Cancer
It’s important to recognize there’s more than one way to detect colon cancer. Other tests can now check stool samples for signs of cancer, much like blood tests check for anemia.
Cologuard is a commonly used, stool-based test for colon cancer that was FDA approved in 2014; a more accurate version was released in 2024. Patients receive a kit in the mail, take their own stool sample at home, and send the kit to a lab for testing. Any positive results are followed up with a traditional colonoscopy.
Because it’s not as sensitive as a colonoscopy (which should be repeated every 10 years), a Cologuard test needs to be repeated every three years.
But Cologuard’s rate of detection is strong. If a colonoscopy detects 10 cancers, Cologuard will detect 9 out of those 10, Dr. Lebwohl says. Several studies comparing stool-based testing with colonoscopy are currently underway, he adds.
“It is often said that the best test is the one that gets done,” Dr. Lebwohl says. “It’s good there’s more than one right way to screen for colon cancer.”
Benjamin Lebwohl, MD, is professor of medicine and epidemiology, associate clinical chief of the Division of Digestive and Liver Diseases, and director of clinical research at the Celiac Disease Center at Columbia University.