What is a colonoscopy? Your questions, answered

You’ve probably heard that a colonoscopy is the gold standard for colorectal cancer screening and prevention. But you may still have questions. What is a colonoscopy? How’s it done? What can I expect?

For answers to these questions and more, we spoke to gastroenterologist David Richards, M.D.

What is a colonoscopy?

A colonoscopy is a procedure in which a long, flexible tube called a colonoscope is inserted into the rectum and around the colon, which is the same as the large intestine. The colonoscope has a camera and light at the tip, which allows the doctor to examine the walls and lining of the colon.

Why is a colonoscopy considered the gold standard test for colorectal cancer?

While there are other, more convenient alternatives to a colonoscopy, including a virtual colonoscopy or stool-based tests, a colonoscopy allows your physician to see the lining of your whole colon, and polyps can be removed right away. Additionally, if there are any issues found in your colon while receiving one of the other tests, you will be referred for a colonoscopy.

How do I prepare for a colonoscopy?

The colon is normally filled with stool, so it must be cleaned out completely before a colonoscopy is administered. You’ll be put on a diet of only clear liquids 24 hours before your procedure, but you must stop consuming any liquids two hours before your procedure. Acceptable liquids are ones you can see through, such as water, Gatorade, broth, and coffee without milk or creamer.

In addition, the night before your colonoscopy, you will need to start drinking a prep solution which you will consume in two rounds – half on the evening before the procedure and the other half on the morning of the procedure. The prep solution works as a laxative, so you’ll use the bathroom several times to clean the stool out of your colon.

How long does a colonoscopy take?

Typically, it takes between 20 and 30 minutes. If the colon is clean and we don’t identify any issues, sometimes it can take as few as 15 minutes.

Will they put me to sleep for a colonoscopy?

Yes, we have an anesthesia team that’s in the room for our colonoscopy procedures. You’ll be put under deep sedation to general anesthesia for your colonoscopy. You’ll be breathing on your own, but you will be asleep. There are unique circumstances where patients request lighter sedation or no sedation. In certain cases, we can honor those requests.

Is a colonoscopy painful?

During a colonoscopy, carbon dioxide gas is pushed through the colonoscope into the colon, so the doctor can better view the colon. When you wake up, you may feel a little bloating, cramping or gassy feeling, but that usually dissipates pretty quickly because carbon dioxide is easily absorbed into the body. Because of the sedation, most people sleep through the entire procedure, experience no pain and wake up with no discomfort.   

What happens if the doctor finds something during my colonoscopy?

The whole goal of the colonoscopy is to identify any potential issues. We’re looking for polyps, which are growths in the lining of the colon. Some polyps are considered precancerous, meaning if they’re left in the colon, they have the potential to turn into cancer later.  

If we see any polyps, we remove them at the time of the colonoscopy. Occasionally, if there is a large or unusual polyp that requires extra time to remove, we schedule a follow-up colonoscopy. If a polyp requires a special removal technique, we will refer you to one of our specialists to have it removed.

If we find a tumor during your colonoscopy, we will take a biopsy to determine exactly what it is and then plan the next steps, whether that’s sending you to a specialist for further examination or a surgeon to remove it.

How long will it take to recover from a colonoscopy?

There is a recovery area where you will remain for about 30 minutes as you fully wake up from your sedation. Nurses will make sure your vital signs are stable and monitor you until the sedation wears off. You’ll be taken down to your car in a wheelchair, and you must have someone available to drive you home. If you are using a rideshare app, you must be accompanied by a responsible adult. We advise you not to drive or lift heavy machinery for 18 to 24 hours after your procedure. By the next day, most patients are back to their normal activities.

When should I get my first colonoscopy?

The current guidelines suggest that everyone should get their first colonoscopy at age 45 if they are at average risk for colorectal cancer. If there’s no family history of colorectal cancer and no polyps are found during the colonoscopy, then you wouldn’t need your next colonoscopy for another 10 years. If we discover polyps during your first colonoscopy, then your next colonoscopy would depend on the size, type or number of polyps that we find.

We start screening earlier for individuals who are at greater risk, such as those with a first-degree relative who had colon cancer. We recommend that if you have a first-degree relative (e.g., parent or sibling) who has had colorectal cancer or precancerous polyps, you should get your first colonoscopy at age 40, or 10 years younger than the age at which the family member was diagnosed, whichever is earlier.

Request an appointment at MD Anderson online or by calling 1-877-632-6789.