What Really Happens During a Colonoscopy

Having a colonoscopy is something people may fear, despite the great benefit that it offers – the ability to diagnose and treat colon and rectal cancer, one of most common types of cancer. Let’s take a look at what really happens before and during a colonoscopy -- to give you an accurate picture and help dispel any anxiety you may have about the procedure.

What Is a Colonoscopy?

A colonoscopy is when a doctor looks inside your large intestine using an instrument called a colonoscope – a flexible tube with a tiny camera at the end. While you are under anesthesia, the colonoscope is inserted into the large intestine through your anus. 

The doctor is looking for abnormal growths called polyps. These may develop into cancer, so finding them early is important to prevent cancer. If the doctor finds an area of concern, a tissue sample can be taken with the colonoscope for later examination under a microscope to look for cancer cells. The doctor may also remove polyps using small surgical tools that are part the colonoscope. 

When to Be Screened?

It’s recommended that you have a preventive screening colonoscopy every 10 years, starting at age 45. People with risk factors, such as a family history of colon cancer, may benefit from starting screening even earlier. Guidelines do change occasionally and your doctor knows the latest recommendations, so they can help you decide when to start screening. 

Why are preventive screening colonoscopies recommended every 10 years? Colon cancer usually develops slowly, taking between seven to 10 years to go from a precancerous polyp to cancer. It’s important to find polyps early so they can be removed and prevent cancer from developing or spreading further. If a colonoscopy doesn’t find any polyps, another screening usually isn’t needed for 10 years. 

Member Cost

The cost of a colonoscopy is something you may be worried about, but this shouldn’t be a concern. Blue Cross will pay for a preventive colonoscopy with no member cost share, if it is performed by an in-network provider and the preventive screening criteria are met. Please note that diagnostic and therapeutic colonoscopies (such as to remove a foreign object or look for the source of abdominal pain) may have a member cost share. 

There are two types of anesthesia that are commonly used during colonoscopies: 

• Conscious sedation is when you are given medications to help you relax and to block pain. You will probably stay awake during the procedure. Conscious sedation does not require prior approval.
• Monitored anesthesia is when an anesthesia clinician monitors you throughout the procedure. The medications you are given typically result in moderate to deep sedation. Monitored anesthesia requires prior approval. If a prior authorization is on file, Blue Cross will pay for this type of anesthesia.

If you have questions about colonoscopy or anesthesia costs, please call our customer service team at the number on the back of your member ID card. 

How to Get One

Colonoscopies are most often performed by gastroenterologists – physicians who specialize in treating conditions of the digestive tract. If you are due for a preventive screening colonoscopy, your primary care provider can refer you to a gastroenterologist’s office.

The gastroenterologist’s office will schedule the procedure and send you information on how to prepare for the colonoscopy.

At Home Preparation

For the patient, preparation is the most involved part of having a colonoscopy. It is important that you follow the instructions you receive carefully. 

• For the colonoscopy to be effective, the doctor needs to have a clear view of your large intestine’s lining during the procedure. This means all the fecal matter that is normally there needs to be thoroughly cleaned out beforehand. 
• If any fecal matter remains in the intestine because of poor preparation, it might conceal the polyps that the doctor is looking for.
• Without a good view of the intestine, your doctor may have to reschedule the colonoscopy and you’ll have to go through the preparation again. It’s important to do it right the first time!

To start preparing, a few days before the colonoscopy you’ll be instructed to switch to a low-fiber diet. This helps reduce the amount of fecal material that will need to be cleaned out of your intestine later. The day before the colonoscopy you’ll only consume clear liquids.

The afternoon or evening before the procedure you’ll be instructed to take a large dose of a laxative like MiraLAX. You may be allowed to mix it with clear soda or light-colored juice to make it taste better. The laxative will quickly trigger a series of bowel movements, so you’ll be spending a lot of time on the toilet over the next several hours. It’s a good idea to have a distraction ready, such as music or reading material to make the time go by more quickly.

The next morning you may be instructed to take another dose of laxative, to make sure you’re all cleaned out. If all that comes out when you’re on the toilet is light-colored or clear liquid, that’s a good sign you’re ready.

A few hours before the colonoscopy, you’ll stop consuming any liquids so that your stomach will be empty when you are under anesthesia. This reduces the chances that you might vomit during the procedure and get some stomach contents into your lungs.

The actual preparation regimen for your colonoscopy may vary, so make sure to follow the specific instructions your provider sent to you.

Upon Arrival

When you arrive at the hospital or freestanding clinic for your colonoscopy, you’ll be directed to an area where nurses will get you ready. A nurse will put an intravenous (IV) line in your arm so that you can be given sedative medications during the procedure. Once you’ve changed into a hospital gown and are lying on a movable bed, you may have to wait a while, so it’s good to have some music or reading material with you to make the time go by and ease any stress you may be feeling.

When it’s your turn, you’ll be wheeled into the procedure room. The nurses will help you get into position, lying on your side. They’ll hook you up to monitors so that they can track your vital signs during the procedure.

Before you’re given any medications, the doctor will probably talk with you for a few minutes and make sure you’re OK about having the procedure. If you have any concerns, be sure to bring them up.
The Procedure

Once the doctor and nurses are ready to begin the procedure, you’ll be given sedative medications through the IV line. You’ll be relaxed, but probably won’t be totally unconscious. You may sleep through the procedure and not remember anything about it later. Some people say they stay awake enough that they can see the images on the monitors the doctor is using. But even if you do stay awake, you shouldn’t feel any pain.

The doctor will insert the long, thin colonoscope into your anus and advance it through your rectum and into the portion of your large intestine called the colon. While the colonoscope is advancing, air is pumped into your colon to inflate it a bit so the doctor can get a better view. As the camera on the end of the colonoscope goes along, the doctor watches images from the camera on a monitor for anything abnormal. Once the end of the colon is reached, the colonoscope is slowly withdrawn and the doctor continues looking for anything abnormal.

The procedure itself usually takes about 20 to 30 minutes. If the doctor removes any polyps, that may add another 15 minutes. Polyps that are removed are later checked by a pathologist to determine if they are cancerous or precancerous.

Recovery and Going Home  

After the colonoscopy is done, you’ll be wheeled to the recovery area to give the medication time to wear off. As you recover, you’ll probably be given some juice or soda to drink. After several hours without anything to eat or drink, the first few sips are sweet -- in more ways than one!

You should expect to stay in the recovery area for about an hour. During that time, the doctor may come in and tell you what they found during the procedure. Some people may not remember what the doctor told them, because they are still groggy, so you may want to have a relative or friend there to listen as well. You will also get a written report or an electronic report in your electronic health record’s patient portal from the doctor’s office. If a tissue sample was taken, you will get the biopsy results later after the pathologist finishes examining the sample.

Because air was pumped into your colon during the procedure, you may have some gas for a few hours. Likewise, you may experience some nausea from the anesthesia. Call your doctor if these persist.   

You may be groggy for a few hours, so having a relative or friend drive you home and take care of you the rest of the day is essential.

After not eating your regular diet for several days, you may be famished and want to have a big meal. Remember that your digestive system has been slowed down and needs time to restart. It’s best to begin slowly with some easy-to-digest foods and then gradually return to your normal diet over a day or two.

As you celebrate completing the colonoscopy with some favorite foods, you can feel good about being screened for colorectal cancer -- and that you probably won’t be due for another screening for 10 years. 

At Home Screening Options

Colonoscopy is considered the best way to be screened for colon cancer, as a physician visually inspects the intestine and can remove any abnormalities before they develop into cancer. If you are not willing to have a colonoscopy, there is an alternative type of screening that you can do at home.

At-home screening tests approved by the Food and Drug Administration are:

• Fecal Immunochemical Test (FIT) – this test detects blood in the stool from bleeding polyps and is considered about 74 percent sensitive in finding colon cancer.
• Cologuard – in addition to looking for blood in the stool, this test includes searching for DNA markers of colon cancer and precancerous polyps. It is considered about 92 percent sensitive in finding colon cancer.

To do either of these tests at home, you’ll need a prescription from your primary care provider to get the test kit, which contains everything you need to collect a sample and send it to a lab for analysis. When the results are ready, your primary care provider will go over them with you.

There are several things to consider about this type of screening:

• They are intended for people with average risk of colorectal cancer. If you have a higher risk, such as a family history of colon cancer, it may be recommended that you have a colonoscopy instead.
• The at-home screening needs to be done more frequently. FIT is repeated annually, while Cologuard is done every three years.
• If a test is positive, a colonoscopy will likely be needed to investigate further and remove any polyps that are found.
• At-home tests may result in false positives.

They’re not perfect, but an at-home screening is better than no screening at all. Colorectal cancer is very treatable if it’s detected early, so please ask your health care provider about which type of screening is right for you.