Colonoscopy contamination problem spreading

Earlier this year, I told you about the widespread problems with contaminated endoscopes, the instruments used to examine the GI tract. The contaminated scopes caused infections and deaths in many good hospitals across the country. The problem baffled many experts since the hospitals complied with the FDA’s standard disinfection procedures. Turns out, a flaw in the instruments’ design makes them virtually impossible to sterilize completely.

I predicted we would find similar problems for the same reasons with colonoscopes, an instrument used to perform colonoscopies. And sad to say, I was right. A new study published in the August issue of American Journal of Infection Control shows the same kind of serious contamination issues with colonoscopes.

According to the new report, hospitals and clinics routinely use a standard, multi-step cleaning and disinfecting process on colonoscopes. Yet the potentially harmful bacteria can still survive. Just add this problem onto the long list of dangers from invasive, expensive, and overused colonoscopy procedures.

Researchers conducted their investigation at a large GI endoscopy unit at one of the country’s finest medical facilities–the Mayo Clinic in Rochester, MN.

First, they monitored decontamination procedures at the Mayo Clinic to make sure the staff complied with the approved guidelines. The approved procedures include bedside cleaning, hand cleaning in dedicated decontamination rooms, and automated, high-level disinfection. Then, after drying the colonoscopes with alcohol and forced air, the Mayo Clinic stores the instruments in a vertical position as recommended.

Overall, the researchers found the Mayo Clinic staff completely complied with the approved decontamination procedures on all the colonoscopes tested. That’s the one bit of good news.

Next, the researchers tested the instruments for evidence of blood and bacterial contamination after each step of the cleaning process. They conducted 60 tests on 15 different scopes during the same first week.

Shockingly, 92 percent of scopes contained live bacteria after bedside cleaning. Plus, 46 percent contained live bacteria after hand cleaning. And a staggering 64 percent contained it after the automated, high-level disinfection.

Even after all the procedures, nine percent of scopes still harbored live microbes while standing in dry storage.

But it gets worse.

Researchers also used a second set of tests called “rapid indicators.” As the name implies, these tests can be done more quickly than culturing and growing bacteria as required in the first set of tests. The rapid indicators also detect the presence of contamination by microbes or blood from use on prior patients.

The rapid indicator tests showed contamination by detection of protein, carbohydrate, hemoglobin, or adenosine triphosphate (ATP) in:

-100 percent of the scopes after bedside cleaning
-92 percent of the manually cleaned scopes
-73 percent of the scopes after automated, high-level disinfection
-82 percent of the stored scopes

Benchmarks for protein, carbohydrate, hemoglobin, and ATP levels have been established to ensure proper cleaning has been completed. But they aren’t yet incorporated into current guidelines. So, health care professionals don’t even know how their scopes stand up, because these kinds of tests aren’t widely performed.

In the rapid indicator tests, the researchers also found evidence of GI microbes, including Escherichia coli, Enterococcus, and viridans streptococci. They also found skin bacteria, including Staphylococcus epidermidis. The researchers even noted clearly visible residue of contamination on many of the materials used to sample endoscopes.

And remember, these results came from the Mayo Clinic. In my opinion, and many others, the Mayo Clinic is one of the best, most patient-oriented healthcare organizations in the world. I regularly quote them regarding their findings and the information they provide to patients. If the Mayo Clinic gets these results, I can only imagine the dreadful situation at the typical profit-driven, industrial scale colonoscopy operation.

Basically, we need more effective methods to clean and disinfect all endoscopes. Including colonoscopes. We also need more widespread testing methods to ensure effective cleaning practices. Including the use of routine monitoring with rapid indicators as well as microbiologic cultures.

But let’s put aside all the issues with contamination for a moment. As I’ve said before, you don’t have to resort to dangerous and uncomfortable colonoscopies. You have several safe, effective screening options.


  1. “Endoscope Contamination Problem Spreads to Simpler Models,” Medscape Medical News ( 8/6/2015
  1. “Persistent contamination on colonoscopes and gastroscopes detected by biologic cultures and rapid indicators despite reprocessing performed in accordance with guidelines,” Am. J. Infection Control 2015; 43:794-801