No one wakes up excited about scheduling a colonoscopy, but the truth is that colonoscopy is one of the most effective tools we have to prevent cancer — not just detect it but prevent it.
Here’s what you really need to know.
A colonoscopy is a screening test that allows a doctor to examine the inside of your large intestine (colon and rectum). Using a thin, flexible tube with a tiny camera on the end, the procedure looks for abnormalities.
It’s typically done as an outpatient procedure and takes about 30 to 45 minutes.
A colonoscopy is primarily used to detect:
- Colon polyps (small growths that can become cancer over time)
- Colorectal cancer
- Sources of unexplained bleeding
- Inflammatory bowel disease
- Changes in bowel habits that need investigation
“Most colorectal cancers start as small polyps,” said Dr. Daniela Abrams, assistant professor in the Gastroenterology & Hepatology Division in the Department of Internal Medicine at UTMB. “During a colonoscopy, doctors can remove those polyps immediately. That means you’re not just screening for cancer — you’re stopping it before it starts.
Colonoscopies are an easy target for comedy, it seems, and often are the butt of jokes in movies and on television. Funny as they can be, these casual references also can encourage some of the common misconceptions about the procedure that can potentially keep people from having it done – such as:
“It’s going to be painful.”
Truth: Most people are sedated and sleep through it. They don’t feel or remember the procedure.
“It’s embarrassing.”
Truth: Medical teams do this every single day. To them, it’s routine health care — not a spectacle.
“If I feel fine, I don’t need one.”
Truth: Colon cancer often has no symptoms in early stages. That’s why screening matters.
“The procedure is the worst part.”
Truth: Ask almost anyone who’s had one — the prep is usually the least pleasant part, not the procedure itself.
Totally normal fears include the bowel prep, being sedated, fear of what might be found, and worry about discomfort or complications
“The good news is that complications are rare, sedation is carefully monitored, and most results are reassuring," Abrams said. “The anticipation is often worse than the reality.”
What to expect
Preparation is critical because your colon needs to be completely clean for the doctor to see clearly.
In advance of your procedure, you’ll typically follow a clear liquid diet the day before, avoid certain foods several days prior (like seeds, nuts or high-fiber foods), drink a prescribed bowel-cleansing laxative solution, and stay near a bathroom during prep (you’ll need it).
Yes, the prep is inconvenient. But it’s temporary — and it’s what makes the test accurate.
During the procedure, you’ll check in and change into a gown, and an IV will be placed for sedation. You’ll lie on your side, and the doctor will gently insert the colonoscope to examine the colon.
If any polyps are found, they’ll be removed right then and there.
The procedure usually takes under an hour, and most patients wake up feeling a little groggy and may experience mild bloating from air used during the exam.
Afterward, you’ll need someone to drive you home. You may feel mild cramping or gas, but no matter how you feel you should plan to rest the remainder of the day. If polyps were removed, you may receive specific instructions.
Most people resume normal activities the next day. While serious complications are uncommon, call your doctor if you have severe abdominal pain, fever, or heavy bleeding.
When should you have your first colonoscopy?
Current guidelines recommend:
- Average-risk adults: Beginning at age 45
- Higher risk individuals: Earlier screening if you have a family history of colorectal cancer and family history of large polyps, inflammatory bowel disease, or certain genetic conditions
“If your colonoscopy is normal, you typically won’t need another for 10 years,” Abrams said. “If polyps are found, your doctor may recommend a shorter interval (often three to seven years). Always follow your physician’s specific recommendation.”
The most important thing doctors want you to know is that colorectal cancer is one of the most treatable cancers when caught early, Abrams said.
“Screening dramatically reduces the risk of dying from it. Many people who develop advanced colon cancer simply never had screening,” she said. “If you’re anxious, talk to your doctor. If you’re putting it off, schedule it. If you're embarrassed, remember that your health, your privacy, and your dignity are our top priorities.”
A colonoscopy may not be the most glamorous item on your calendar. But it might be the most important one.
And once it’s done? Most people say the same thing – “That wasn’t nearly as bad as I thought it would be.
Schedule your Annual Wellness Visit and talk with a primary care provider about colorectal cancer screening options.