"If you don't have a standardized process across the board and if you don't review it on a regular basis, then you can find that problems slip through," said Dr. David Armstrong, the Canadian Association of Gastroenterology's lead for its quality committee.
Hotel-Dieu de Levis hospital, located east of Quebec City, is currently in the process of notifying about 1,000 patients who underwent endoscopic ultrasound exams since mid-2005. They are being asked to come in for testing for HIV and hepatitis B and C, which could've been transmitted from the improperly cleaned machine.
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The endoscopic ultrasound procedure involves a thin, flexible endoscope mounted with a camera, which is inserted through the mouth to examine a patient's digestive system using sound waves.
Each endoscope requires a complex and specific multi-stage cleaning process dictated not only by provincial and federal guidelines, but also by the manufacturer.
The hospital says in this case, it wasn't following the manufacturer's specific guidelines for this specialized endoscope.
"Endoscopes are particularly complex and difficult to clean because they've got very long, very narrow channels," said infection prevention and control expert Dr. Mary Vearncombe. "It's very difficult to make sure that those channels are flushed and disinfected properly in between uses, just because their diameter is so very narrow."
Dr. Armstong said the late discovery highlights a need to regularly review whether the team in charge of cleaning endoscopes is doing it properly.
He says the issue is analogous to the deadly E. coli contamination of the water supply in Walkerton, Ont. in 2000. In that case, procedures were in place to ensure safe drinking water, but checks weren't done to ensure the processes were followed.
"One knows what needs to be done to produce a safe water supply, but if the appropriate checks are put into place but they are not monitored and verified, then it's possible to assume that everything's OK and the processes are being followed without actually documenting that its actually done on a daily basis or a weekly basis," said Armstrong, a McMaster University associate professor and consultant gastroenterologist at Hamilton Health Sciences.
Every year, about 1.6 million endoscopic procedures are performed in Canada, a figure representing about five per cent of the population.
Despite how common the procedure has become, hospitals tend to track incidents of improper endoscope cleaning that result in patient harm on an ad-hoc basis, says Armstrong. That means the public only learns of problems when the media covers large-scale events disclosed by the hospital.
"From the point of view of how often it actually happens, it's actually very difficult to know, because without appropriate tracking mechanisms, this may just go undetected," he said.
Dr. Armstrong said the Canadian Association of Gastroenterologists has encouraged Accreditation Canada — a non-profit organization that accredits hospitals — to include endoscopy cleaning in its reviews of hospital's sterilization procedures, since many endoscopy cleaning units are separate from the central sterilization processes.
However, Dr. Vearncombe, medical director of infection control at Toronto's Sunnybrook Health Sciences Centre, says the risks in incidents such as the one at the Quebec hospital are "almost immeasurably low."
Risk 'not zero'
In many such large-scale adverse events, few or no patients are affected, she said. Such was the case for Sunnybrook hospital in 2003, when it was discovered that a prostate biopsy machine hadn't been cleaned properly.
The hospital contacted more than 900 men to test them, and not one infection linked to the machine was found. Despite that, however, a class-action lawsuit was filed arguing patients endured psychological harm. The hospital settled out of court, without admitting liability.
In a similar case, a private endoscopy clinic in Ottawa was found to have used poor sterilization methods for nearly a decade. A year-long, $770,000 public health investigation turned up no cases of infection linked to the endoscopes among the thousands of patients tested.
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"I think there's been a lot of discussion around the fact that the risk is low [in Quebec]," said Dr. Armstrong. "The trouble is, it's not zero."
A 2010 study, The Disclosure Dilemma - Large-Scale Adverse Events, found that of nine incidents of contaminated medical equipment, including the Sunnybrook case, that researchers examined, five resulted in physical harm, but the incidence rate was very low.
But as Dr. Vearncombe notes, it's important to remember that every situation is different.
"Each piece of equipment is different and what particularly failed in the cleaning and sterilization process is always different," said Dr. Vearncombe.