Many hear “colonoscopy” and think only about the prep. But do you know what happens before, during, and after a colonoscopy procedure? Find out here.

It’s not your grandparents’ colonoscopy anymore. Heck, it’s not even the colonoscopy you might have had 10 years ago.

We’re not talking about the preparation for fasting and bowel cleansing, but about the actual colonoscopy procedure. This gold-standard test for detecting and removing precancerous growths in the colon has advanced much in just the past five years, thanks to technologies that have made it more effective and accurate.

Learn about the latest in colonoscopy procedures here.

For example, did you know many leading gastroenterologists, including those at Cincinnati GI, now offer artificial intelligence-assisted colonoscopies that can better detect colorectal polyps?

Yet in 2025, 57% of U.S. adults did not know colonoscopy screenings can actually prevent colorectal cancer from developing, according to a survey by the Colorectal Cancer Alliance. Of the respondents, 98% said they’d more likely undergo the screening knowing that.

The point is that to prevent cases of colorectal cancer, we need to improve understanding. March is National Colorectal Cancer Awareness Month, one effort to do so. This blog is our effort to raise awareness of what patients – even those who have had colonoscopies before – can expect from the procedure today – before, during, and after.

Let’s Start By Defining ‘Colonoscopy’

First introduced in 1969, the colonoscopy is a routine outpatient procedure that enables a physician to clearly view, in real time, the inside of a patient’s colon (large intestine). Medical experts and the Food and Drug Administration consider it the most reliable and effective approach to colorectal cancer screening.

However, a colonoscopy is also a cancer-prevention procedure because, in addition to enabling a physician to identify ulcers, inflammation, and polyps (growths that can become cancer), the instruments used in a colonoscopy can remove them. Anything taken from the colon is biopsied for evidence of cancer to determine the patient’s likelihood of developing the disease.

Today, doctors perform more than 15 million colonoscopies a year. Researchers estimate the test reduces the incidence of colorectal cancer by 40% to 69%, and the overall death risk by roughly 60%.

How the Colonoscopy Procedure is Performed

You most likely won’t be awake during your colonoscopy screening, but here is what to expect.

Upon arrival at the gastroenterologist’s office, you’ll be provided a patient’s gown to change into (your clothes will be securely stowed). A nurse will then guide you to a gurney and insert an I.V. for eventual sedation. Soon, your gastroenterologist and anesthesiologist will visit you to explain the procedure before you are brought into the examination room, asked to lie on your side, and lightly sedated.

The gastroenterologist begins the screening by gently inserting a narrow, camera-equipped tube called a colonoscope through the rectum into the colon. As the flexible scope travels the length of the colon, the video camera sends detailed images of the intestinal lining for the doctor to examine.

If the images reveal polyps, the doctor removes them immediately with a tiny, looped wire fed through the colonoscope, then sends them to a lab for examination.

Among recent innovations in this process is the development of AI-assisted colonoscopy screenings. In 2024, Cincinnati GI began offering GI Genius, a computer-aided polyp-detection system guided by artificial intelligence that provides a second observer and sharper visualization. Patients can ask about this option when scheduling.

Will the Colonoscopy Procedure Hurt?

A colonoscopy should be painless, even if polyps are found and removed, because you will likely be completely sedated.

After the procedure, you might experience mild, gas-like cramping for about a day, owing to a small amount of air the doctor uses to open up your colon for improved visualization.

If the doctor removed polyps, you might experience mild discomfort the following day (bleeding is rare).

How Long a Colonoscopy Takes, and What Happens After

A routine colonoscopy typically takes 15 to 20 minutes after sedation takes effect, but it can last 30 to 60 minutes if the doctor removes polyps or growths and takes biopsies.

In either case, plan to be at the gastroenterologist’s office for two to three hours. This accounts for the time spent preparing and sedating you before the screening, and for recovery, during which your doctor will review the results.

It can take 10 to 15 minutes to fully awake from sedation, during which you likely will feel lightheaded and “dreamy.”

When you are fully awake, your doctor will share the results. When you can stand, you can get dressed to leave, but you will need a driver to take you home safely. You should stay home for the remainder of the day. Plan to take off from work.

What Happens if the Colonoscopy Reveals Polyps

If polyps are identified in your colon, your gastroenterologist will remove them during the colonoscopy procedure. If the polyp is too large to remove entirely, the gastroenterologist will take a biopsy (a tissue sample).

The number of polyps found is less concerning than the type, as some are benign, while others show abnormal cell activity (dysplasia). Typically, the combined number, size, and type of polyps determine cancer risk.

Should your care team determine the polyps present a cancer threat, you might need surgery to remove malignant growths that could have extended into the colon wall. An endoscopic resection, for example, treats early-stage cancers by removing abnormal tissue in an outpatient setting.

When You’ll Have to Come Back for the Next Colonoscopy

If you have a clean colonoscopy, congratulations! You likely will not require another screening for 10 years (unless you have a family history or are otherwise at high risk). If you had polyps, there are two scenarios:

• If the polyps are benign, you likely will be advised to return after three years, but you may be required to get more frequent screenings depending on the polyp type, size, and number.
• If you had pre-cancerous polyps, your doctor might advise a follow-up screening in as soon as six months to every one to three years, to examine the area where the polyps were removed.

Have You Been Putting Off a Colonoscopy?

Here’s another way today’s colonoscopy is different from those of your grandparents: Researchers now advise everyone at normal risk to get their first colonoscopy by age 45. Those with family history, inflammatory bowel disease, or other high-risk factors should ask their doctor about getting a colonoscopy as young as 40 or earlier.

Talk to your doctor about when to schedule your first or next colonoscopy. We’re still innovating to make it more effective and comfortable for you.

Curious to know more? Download our handy infographic, The Value of a Colonoscopy. You can request an appointment online right here.