June 11, 2018
Should Endoscopes Be Sterilized Or Not?
By Michael D. Shaw
Last October, this column discussed the problem of properly reprocessing flexible endoscopes. “Reprocessing” is defined as validated processes used to render a medical device, which has been previously used or contaminated, fit for a subsequent single use. These processes are designed to remove soil and contaminants by cleaning and to inactivate microorganisms by disinfection or sterilization.
The October column appeared not long after the Association for the Advancement of Medical Instrumentation (AAMI) issued a press release entitled “Strong Evidence for Sterilization of Endoscopes Presented at Stakeholder Meeting.” The subtext being that currently most scopes undergo high-level disinfection, and not sterilization.
Sterilization destroys all microorganisms, including bacterial spores. High-level disinfection (HLD) destroys all micro-organisms except high numbers of bacterial spores. (Detailed reference). Or, as the sick joke puts it: High-level disinfection is used when you are the patient; sterilization is used when I am the patient.
Bear in mind that sterilization is generally more expensive and time-consuming than high-level disinfection. Meanwhile, the plot thickens. In March, 2018, the American Society for Gastrointestinal Endoscopy (ASGE) published a Guideline, entitled “Infection control during GI endoscopy.” This 7000-word document was referred to by a friend of mine as “The Empire Strikes Back” since it is diametrically opposed to the AAMI posting.
Consider these remarks from the ASGE Guideline:
1. Because of these factors [complexity of instrument design; potential damage to scopes by sterilization] as well as a lack of data for demonstrable benefits to the further reduction in endoscope bacteria spore counts achieved by sterilization instead of HLD, sterilization with ethylene oxide is not recommended over HLD for standard GI endoscopes.
COMMENT: Of course, “complexity of instrument design” poses challenges to HLD, as well. While ASGE notes “a lack of data,” oddly, they don’t seem to be clamoring for such studies to be done. Likewise, reports of scope damage are, by definition, anecdotal, and this matter should also be properly studied.
2. Transmission of infection as a result of GI endoscopes is extremely rare, and most reported cases are attributable to lapses in currently accepted endoscope reprocessing protocols or to defective equipment.
COMMENT: Unfortunately, not as rare as ASGE would have you believe, in light of a new study from Johns Hopkins, which we now discuss.
This study, entitled “Rates of infection after colonoscopy and osophagogastroduodenoscopy [OGD] in ambulatory surgery centres in the USA” was published in Gut on May 18th. Researchers examined data from six states—California, Florida, Georgia, Nebraska, New York, and Vermont—to track infection-related emergency room visits and unplanned inpatient admissions within seven and 30 days after either of the two procedures. Since many of these surgery centers lack an electronic medical record system connected to hospital emergency departments, those institutions are unlikely to learn of their patients’ infections. Here are some key findings:
1. The rates of infection following colonoscopies and upper-GI endoscopies performed at U.S. outpatient specialty centers are far higher than previously believed. At some facilities, the rate is 100 times what was expected.
2. The rates of postendoscopic infection per 1000 procedures within 7 days were 1.1 for screening colonoscopy, 1.6 for non-screening colonoscopy, and 3.0 for OGD. Rates of 7-day postendoscopic infections varied widely by surgery center, ranging from 0 to 115 per 1000 procedures for screening colonoscopy, 0 to 132 for non-screening colonoscopy and 0 to 62 for OGD.
So, what are we to conclude? The ASGE Guideline seems a bit self-serving, given the cavalier manner in which it dismisses sterilization. While the Hopkins study is silent on the matter of sterilization versus HLD, it certainly blows the doors off the “Transmission of infection as a result of GI endoscopes is extremely rare” narrative. What’s needed now is for more facilities to use sterilization—perhaps under grant support—so that a meaningful comparison study versus HLD can finally be run.