When your car needs servicing, you want a mechanic who is honest and reliable.  When you need to hire a lawyer, you want someone who knows your area of need and has a record of success.  Do you exercise the same level of scrutiny when you schedule a colonoscopy?  You should.


Adenomas in the colon (i.e., the large intestine) are benign tumors that have the potential to turn into cancers.  Screening colonoscopies can detect these tumors and the colonoscopist can remove them without doing another procedure.  Widespread screening has reduced colon cancer and related deaths by detecting and removing cancers at a stage when they are more treatable.

How Good Is Your Colonoscopist?

A recent study examined colonoscopists’ adenoma detection rates (ADRs: the percentage of colonoscopies where at least one adenoma was found) in performing colonoscopies and compared the rates to the subsequent development of colon cancers.  Kaiser Permanente’s vast store of medical records supplied the data, and 852,624 colonoscopies were analyzed.  To make a long and somewhat complicated story short, the patients of physicians with lower ADRs had almost double the incidence of colon cancers compared to patients of physicians with higher ADRs (3.10 vs. 1.79 per 10,000 patient years).  And the higher the ADR, the better.  

Measuring Effectiveness

Currently, the minimum ADR for acceptable performance of colonoscopies  is 25 percent, according to an article published in Gastrointestinal Endoscopy in 2014. Alarmingly, in a survey of 250 gastroenterologists who perform more than 80 colonoscopies per month, 20 percent responded that they did not keep track of their ADRs.  Even more alarmingly, the worst performers miss more than 90 percent of the colonic adenomas.  

Nevertheless, overall, screening colonoscopy reduces the risk of death from colon cancer by about 70 percent.  Think how much better it could be.  For your next colonoscopy, ask your colonoscopist what his or her ADR is.  If the information is not available, find a colonoscopist who keeps track of this vital statistic.


  1. Wendy says:

    Thanks for this–I had no idea!

  2. Anonymous says:

    Thanks for the advice. The last guy I had for a colonoscopy said I had two pre-cancerous polyps. What am I supposed to do with that information?

    1. jpwmd says:

      One of the good things about colonoscopies is their therapeutic nature if an adenoma is found. The colonoscopist can remove most of the adenomas without need for further intervention. If he did not make it clear, you should ask him if he removed the polyps.

    2. jpwmd says:

      As a physician (retired)I guess I could be considered a sophisticated consumer of healthcare. I had never heard of ADRs.

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