Colonoscopy: Preparation, Risks, Alternatives

An estimated 135,000 people are diagnosed with colorectal cancer each year.

Colonoscopy is the screening usually done to test for colon cancer, which is the second leading cause of cancer-related deaths in the United States.

Historically, colon cancer has been confined to those over the age of 50, although that may be changing.

Are you at risk of colon cancer?

The rate of colon cancer mortality among young adults has risen by about 1 death per 100,000 among young adults, to a 3-in-100,000 risk.

Consequently, younger people are now urged to consider colon cancer screening, which is typically done by colonoscopy. During a colonoscopy, your doctor will remove polyps (abnormal growths) before they transform into cancers.

However, the risk of death from colonoscopy is anywhere from 1 out of every 16,318 procedures, to 1 for every 1,000 procedures, depending on the source.

This means that if you’re in your 20s and 30s, your mortality risk from colonoscopy is FAR greater than your risk of colon cancer! In fact, if you are a young adult you maybe three times more likely to die from the screening procedure than the disease itself.

With some 15 million colonoscopies being done each year in the U.S. that means as many as 15,000 Americans die each year as a result of this routine screening.

Screening tests for Colon Cancer

Men and women over the age of 50 at average risk of colorectal cancer are typically recommended to get tested either by:

  • Fecal occult blood testing (FOBT) looks at the blood in your feces.  If the results show that there is blood, it could be a sign of a problem in your digestive systems, such as a growth, or polyp, or cancer in the colon or rectum.

  • A barium enema is an X-ray exam that can detect changes or abnormalities in the large intestine (colon). The procedure is also called a colon X-ray. An enema is the injection of a liquid into your rectum through a small tube.

  • Flexible sigmoidoscopy is a procedure in which a medical professional uses a flexible, narrow tube with a light and tiny camera on one end, called a sigmoidoscope to look inside your rectum and lower colon. A sigmoidoscopy is less invasive, covering only the lower part of the colon, also known as the rectum and sigmoid colon. Sedation is usually not needed, and the screening is done every five years.

  • Colonoscopy is recommended every 10 years. During the procedure, the doctor puts a tube-like instrument called a colonoscope into your rectum. It has a light and a video camera on the tip so the doctor can see the lining of your colon and tell if there is any problem.

What are the risk factors for Colon Cancer?

  • You are male

  • You’re African American

  • You or someone in your family has had colon polyps or colorectal cancer

  • You have a personal history of inflammatory bowel diseases, such as ulcerative colitis and Crohn’s disease

  • You’ve got Lynch syndrome or another genetic disorder that increases the risk of colorectal cancer

  • Smoking and being overweight

How do I prepare for a Colonoscopy?

Colonoscopy prep involves changing your diet a few days prior to the procedure. Begin by eating a low fiber diet and the day before the colonoscopy you should not consume any solid foods.

Instead opt for a liquid diet, including clear broth, bouillon, black coffee or tea. You should follow a clear liquid diet on the actual day of the procedure a. You should also not eat or drink anything two hours beforehand. 

Bowel prep for Colonoscopy

Bowel preparation before a colonoscopy is important.  Your doctor will give you written bowel prep instructions to follow before you have the procedure. This is so little stool remains in your small intestine. 

Why do Doctors use Colonoscopy?

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths in the United States. Screening colonoscopy can prevent CRC by the detection and removal of precancerous lesions, abnormal growths, and colon polyps.

However, while colorectal cancer screening may find diseases at an early stage, it can result in a number of severe complications.

Colonoscopy complications

Serious complications for colonoscopy also occur at a rate of about 1 per 200 to 350 procedures, again depending on the source of the data. Here are the side effects that can arise from colonoscopy.

  • Perforation of the colon, which occurs at a rate of 1 in 800 (people at higher risk include those with diverticulitis, diseases of the colon and adhesions from pelvic surgery). Research shows the risk of death subsequent to perforation is nearly 52 per 1,000 colonoscopic perforations and 64.5 per 1000 sigmoidoscopic perforations.

  • Dysbiosis and other gut imbalances, caused by the process of flushing out your intestinal tract before the procedure with harsh laxatives.

  • Bleeding, rectal bleeding and abdominal pain

  • Complications from the anesthesia. Many experts agree you should opt for the lightest level of sedation possible, or none at all, as full anesthesia increases risks.

  • Infections caused by poorly disinfected scopes.

  • False positives. According to the Prostate Cancer Foundation, an estimated 30 to 40 percent of men treated for prostate cancer have harmless tumors that would never have caused problems in their lifetime. As noted by Jessica Herzstein, a preventive-medicine consultant and member of the U.S. Preventive Services Task Force, “you’re going to die with them, not of them.”

False positives lead to unnecessary treatments that are nearly always harmful, in addition to the anxiety a cancer diagnosis brings. For example, incontinence and erectile dysfunction are two common side effects of radiation therapy. Hormone therapy has also been linked to osteoporosis and depression.

What are the alternatives?

One alternative to colonoscopy is an x-ray virtual colonoscopy (ct colonography). However, that x-ray raises your lifetime risk of all forms of cancer by 20%. Killing you with another form of cancer before the colon gets affected is one hell of a way to prevent colon cancer.

Another alternative to a colonoscopy is a far safer sigmoidoscopy. This tends to have 10 times fewer complications, yet most doctors still recommend colonoscopy 95% of the time.

There is a non-invasive procedure called the FOBT stool test. However, part of the reason that this is not offered by most doctors is that they typically do get a financial kickback when referring patients to a procedure such as a colonoscopy. It is in your interest to insist on this non-invasive test.

If you do have an invasive procedure for screening your Colon, check out their procedure for cleaning the tools after each use. These kinds of tools cannot be heat sterilized and the disinfection techniques and agents used 80% of the time are grossly inadequate.

What questions should I ask before having a colonoscopy?

Infections can easily be passed from patient to patient and considering multidrug-resistant bacterial infections are on the rise; this is a significant risk. So ask your gastroenterologist the following questions.

  • How is the endoscope cleaned between patients?

  • Specifically, which cleaning agent is used?

  • If the hospital or clinic uses peracetic acid, your likelihood of contracting an infection from a previous patient is slim.

  • Glutaraldehyde, or the brand name Cidex (which is what 80 percent of clinics use), does NOT properly sterilize these tools. If glutaraldehyde is used, cancel your appointment and find a clinic that uses peracetic acid.

  • How many of your colonoscopy patients have had to be hospitalized due to infections?

Asking these questions could literally save your life.


Of course, the safest way to deal with colorectal cancer is prevention.

Colorectal cancer is the second leading cause of cancer deaths in the U.S. Yet evidence suggests it is preventable using simple lifestyle changes.

Excessive levels of animal protein especially processed meats have been linked to colorectal cancer. Processed meats are classified as a Group 1 carcinogen as it poses the same cancer risk as smoking and asbestos.

The safest diet for you should be one that gives you most of your calories from vegetables and good fats. In other words the ketogenic diet. See more about that on my website.

It is also an excellent idea to exercise regularly. One study revealed physically active men and women have about a 30 percent to 40 percent reduction in the risk of developing colon cancer compared with inactive persons.

Explore More

how to prevent colon cancer

7 Ways To Prevent Colon Cancer.


  1. Bonnington SN, Rutter MD. Surveillance of colonic polyps: Are we getting it right?. World J Gastroenterol. 2016;22(6):1925–1934. doi:10.3748/wjg.v22.i6.1925
  2. Johnson, D, Barkun, A, Cohen, L ,Dominitz, J, et al. (2014). Optimizing Adequacy of Bowel Cleansing for Colonoscopy: Recommendations From the US Multi-Society Task Force on Colorectal Cancer. Gastroenterology . 147 (4), p903–924.
  3. Lee, IM . (2003). Physical activity and cancer prevention–data from epidemiologic studies.. Medicine & Science in Sports & Exercise. 35 (11), p1823-1827.
  4. Lin, J.S., Piper, M.A., Perdue, L.A. et al. Screening for colorectal cancer: Updated evidence report and systematic review for the US Preventive Services Task Force. JAMA. 2016; 315: 2576–2594
  5. Wang, L., Mannalithara, A., Singh, G. et al. Low rates of gastrointestinal and non-gastrointestinal complications for screening or surveillance colonoscopies in a population-based study.Gastroenterology. 2018; 154: 540–555
  6. W.Ko, C. (2018). Colonoscopy Risks: What Is Known and What Are the Next Steps?. Gastroenterology. 154 (3), p473–475.

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