Is It Time for a Colonoscopy?

Luna Asrar, MD is a board-certified primary care physician practicing family medicine at Inova Primary Care – Ashburn Filigree Court. She enjoys treating people of all ages, with a special interest in health promotion and disease prevention.

Seeing the bigger picture is important — especially when it involves screening for colorectal cancer (also called colon cancer). For some people, the screening process can feel scary and cause anxiety. But the bigger picture is that finding colorectal cancer early saves lives.

Why Colorectal Cancer Screening Guidelines Matter

More than 150,000 American adults are diagnosed with colorectal cancer yearly — that’s one out of every 24 people. Colorectal cancer used to be considered a late-onset disease (primarily diagnosed in people over 50). But rates of colorectal cancer have consistently declined in older adults while increasing for people younger than 50. Some experts believe that by 2030, colorectal cancer may be the leading cause of cancer death in adults under age 50.

In response, the U.S. Preventive Services Task Force (USPSTF) revised their screening recommendations in 2021, bringing the starting age for colon cancer screening from 50 to 45. All adults 45 to 75 at average risk should get screened every 10 years. If you have an increased risk for colorectal cancer, talk to your primary care physician (PCP) about when to begin screening and how often to get tested.

Detecting colorectal cancer early gives you a better chance of survival — the cancer is more likely to be small, treatable and not metastasized (spread to other areas of the body). When physicians identify colorectal cancer before it spreads, the 5-year relative survival rate is 90% (meaning 90% of people will live five years or more). Once cancer spreads, the survival rate is much lower.

Why Is a Colonoscopy Procedure the Most Effective Screening Tool?

A colonoscopy is the single most important tool for the prevention and treatment of colorectal cancer. Many experts refer to colonoscopy as the “gold standard” of screening. It’s the only screening tool that provides a complete view of the entire colon and offers cancer prevention as well as detection.

A colonoscopy allows your doctor to look inside your colon and rectum with a camera.

During the procedure, you’ll sleep under general anesthesia as your provider uses a long, flexible tube equipped with a light and a camera. They are looking for tumors or polyps — small clumps of non-cancerous cells in the colon’s lining. If they detect something, they can use small instruments passed through the tube to remove it — often before it can develop into cancer.

Diagram showing inside colon with colonoscope illustration

Preparing for Your Colonoscopy Procedure

Before your colonoscopy, your provider will give you specific instructions on preparing. The preparation will include cleansing your colon so it’s easier to spot and remove polyps. Cleansing your colon usually requires eating white foods (such as rice, bread and potatoes) for several days and then having a clear liquid diet the day leading up to the procedure. Your physician will also prescribe a liquid laxative to help empty your bowels.

To make the process easier, make sure to:

  • Learn about the procedure because the more you know, the less anxious you’ll feel.
  • Ask your health care provider questions about the preparation and procedure.
  • Set yourself up to succeed by stocking your kitchen with the items you’ll need and making sure you have access to a bathroom the day before your colonoscopy.
  • Follow the instructions because if your colon is not thoroughly clean, you may need to repeat the procedure.

Other Options for Colorectal Cancer Screening

Some people cannot or choose not to have a colonoscopy procedure — they may have had a bad experience previously, are at risk for complications or can’t physically get to the clinic. The good news is that there are other options for colorectal cancer screening:

At-Home Colon Cancer Tests

At-home tests evaluate a sample of your stool to screen for colorectal cancer. They’re not as effective at detecting cancer as colonoscopies, but they are noninvasive and inexpensive. You can also conduct the screening without leaving the comfort and privacy of your home.

At-home colorectal cancer tests include:

  • Cologuard®: This test looks for specific DNA markers and blood in your stool. It screens with nearly 90% accuracy — but DNA tests tend to have more false positives (detects cancer that may not be there). If the test is negative, you’ll repeat it every three years. If there is a positive result, the next step is a colonoscopy.
  • FIT Test: The fecal immunochemical test (FIT) looks for blood in your stool. The test should be done annually and is nearly 80% accurate. If you opt for a FIT-DNA test, the test also looks for DNA markers and is more accurate for detecting colorectal cancer.
  • Guaiac-based fecal occult blood test (gFOBT): This test checks for blood in the stool, but it requires certain restrictions in preparation — such as dietary changes and no pain relievers. The gFOBT test is about 71% accurate.

Virtual Colonoscopy

A virtual colonoscopy uses low-dose computed tomography (CT) scanning to produce images of the colon. A CT colonoscopy doesn’t require sedation and is less invasive than a traditional colonoscopy. But it also doesn’t provide a view of the entire colon or allow the removal of polyps. Your doctor may recommend a virtual colonoscopy if you couldn’t have a colonoscopy or the test was incomplete.


A sigmoidoscopy, like a colonoscopy, uses a flexible tube and camera to look inside the colon. But a sigmoidoscopy only investigates the lower part of your colon. If your provider finds polyps during a sigmoidoscopy, you’ll need a colonoscopy to remove them.

Deciding Which Colon Cancer Screening Test is Right for You

No matter which test you use, try not to delay your colonoscopy more than necessary. Talk to your PCP to assess your risk and determine the right timing and type of test for your colorectal screening. If you do not have a PCP, we welcome you to make an appointment with a provider at any of our Primary Care locations.

To find out more about colorectal cancer screening, schedule an appointment with your Inova Gastroenterologist using your MyChart patient portal. If you do not have a Gastroenterologist, we welcome you contact us to make an appointment with a provider at any of our GI locations.


  1. Terry on February 16, 2023 at 11:17 am

    Thank you. This is a very informative article.
    I didn’t know data indicates “Some experts believe that by 2030, colorectal cancer may be the leading cause of cancer death in adults under age 50.”

  2. Chris on February 22, 2023 at 11:13 am

    I did not look forward to drinking all the ‘terrible-tasting’ liquid, so I had my PCP prescribe Cologuard, which was easy, but you can get both false positives and negatives…thank god, mine was a false positive. With the false positive, I then scheduled a colonoscopy…the preparation and the actual procedure was very easy, and I got a clean report 👍. The real problem with the Cologuard option is if you get a false negative, and walk around for three years thinking you are healthy while a cancer could be growing and spreading in your body. I am a big proponent of a real colonoscopy, and that is the recommendation that I provide to all families and friends.

  3. Phil on February 23, 2023 at 12:02 pm

    I’ve had 2 colonoscopies so far, 10 years apart. Not a big deal. And the peace of mind more than worth it.

  4. J on February 24, 2023 at 9:57 am

    Sedation is not required. If you can stand a little pain, stay awake to watch the process.

  5. Betty on February 27, 2023 at 10:50 am

    Can you drive after the test

  6. Greg on March 2, 2023 at 10:47 am

    One of the biggest deterrents to individuals getting a colonoscopy is handling the Prep, usually PEG powder dissolved in a liquid. My first two experiences were a disaster trying to swallow eight glasses of PEG solution which felt like I was drinking oil. For my most recent colonoscopy, my gastroenterologist recommended I mix the PEG powder with Gateraid and split it into two periods, one the night before my procedure and the second the morning before my afternoon appointment. This was significantly, and I mean significantly more tolerable. The Gateraid masked almost all of the oily texture of the PEG in solution and drinking four glasses at two different times helped a lot. Why doesn’t the gastroenterologist community recognize this and standardize this process? You would gain a lot of participants by making this so much more tolerable.

  7. Barbara on March 17, 2023 at 3:31 pm

    Concern more than a comment. My husband was told not to take any blood thinners before the colonoscopy and he is concerned if taking one could lead to bleeding. He was told my someone that his friend took a blood thinner and died because of the procedure. Should he be concerned if he doesn’t take his blood thinner days before the exam?

  8. Isabella on May 8, 2023 at 1:19 pm

    ALL TESTING IS PERSONAL and serious: The rules have changed w/ colonoscopies: one must be fully sedated, at at INOVA ALEXANDRIA hospital and the Gastroenterologist group, (Digestive Disease and Physician’s group) and one cannot drive because the day of Vercet or light anesthesia are over, ONE CANNOT DRIVE after a colonoscopy because the anesthesia so arrangements must be made.

    As far as the PREP.. or cleansing of the colon: it is as bad as ever. I had five colonoscopies after a “cancer scare” and I am retired from medicine. ALL PROCEEDURES in hospital are serious, between the IVs and possible colonic perforations .. be sure you know your doctor WELL. Good luck

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