The effectiveness of a sterilization process is contingent upon a successful preparation phase, the proper operation of equipment, and the expertise of the reprocessing technician. Currently, most flexible endoscopes are subjected to high-level disinfection (HLD), with only a limited number validated for sterilization, despite a growing number of infections and outbreaks reported by the Food and Drug Administration.
Earlier this year, the FDA announced it is investigating the source of 450 infections associated with patients who underwent procedures involving urological endoscopes. These cases, which occurred between January 2017 and February 2021, are documented in Medical Device Reports submitted to the FDA. According to the FDA, inadequate reprocessing of the scopes used in these procedures could cause infections.
In an April letter regarding these investigations, the agency recommended high-level disinfection or low-temperature sterilization to mitigate infection risks. These incidents and subsequent investigations have sparked a debate among experts about the most effective reprocessing method for these delicate instruments to ensure patient safety.
Keeping It Clean
Sterilizing flexible endoscopes is important. While most flexible endoscopes typically undergo high-level disinfection, sterilization remains a crucial part of their reprocessing, along with their accessories. However, a common misconception is that if items are placed in a sterilizer and the cycle is completed, those items are automatically considered sterile.
This is far from the truth.
In reality, the device cannot be deemed sterile if the steps leading up to sterilization are not meticulously performed. For sterilization to succeed, proper cleaning, testing, inspection, assembly, positioning, packaging and loading must be done correctly.
Cleaning an endoscope is recognized as the most vital step in its reprocessing. Inadequate cleaning can leave residual debris that obstructs effective disinfection, significantly increasing the risk of infection transmission to patients. This concern is amplified by the sensitive nature of the internal channels and the likelihood of significant bacterial contamination from bodily fluids encountered during procedures. Ultimately, the guiding principle remains: “You can’t disinfect what isn’t clean.”
Cleaning is imperative because any delay in the process allows organic material to stay on the endoscope, forming a biofilm. This biofilm effectively shields bacteria, making them far more challenging to eliminate. Strong disinfectants or sterilants often fail to penetrate through residual debris, leaving pathogens viable and posing a risk of transmission to other patients. Due to the critical infection risk, healthcare facilities are obligated to follow stringent guidelines for endoscope reprocessing to ensure the prevention of infection transmission.
According to Cori Ofstead, MSPH, founder and CEO of the medical research firm Ofstead & Associates, the sterilization process is “more rigorous than high-level disinfection and provides a much larger margin of safety.”
Sterilization offers much greater assurance of eliminating microbes and provides a substantial safety buffer against potential patient infections. This is due to the more thorough kill rate achieved during sterilization. Sterilization is often characterized by a significantly more significant “log reduction” than disinfection, typically reaching a higher log10 reduction of microbes. This underscores the critical importance of sterilization in ensuring patient safety in healthcare settings.
The Best Agent for the Job
There are a few methods for sterilizing endoscopes today: ethylene oxide (EtO), vaporized hydrogen peroxide (VH2O2), paracetic acid, and plasma. EO is not commonly used but still exists in some areas. EtO is a colorless, flammable gas used mainly as a sterilizing agent for medical equipment and certain food products like spices, as it can effectively kill bacteria even on materials that cannot be sterilized with heat; however, due to its potential to cause cancer with prolonged exposure, it is considered a hazardous air pollutant, and its use is strictly regulated by environmental agencies like the EPA.
Vaporized Hydrogen Peroxide
VH2O2 is a form of hydrogen peroxide that exists as a vapor. It is harnessed primarily for its antimicrobial properties in various sterile environments. This versatile agent decontaminates enclosed spaces such as hospital rooms, laboratory workstations and aircraft interiors, playing a critical role in infection control and bio-decontamination processes. One of the standout features of VH2O2 is its effectiveness in sterilizing heat-sensitive medical devices. Traditional sterilization methods, such as autoclaving, rely on high temperatures that could damage delicate instruments.
In contrast, vaporized hydrogen peroxide can effectively eliminate many pathogenic microorganisms, including bacteria, viruses, and fungi, without requiring elevated temperatures. This property makes it particularly valuable in hospitals and other healthcare settings where maintaining the integrity of medical instruments is crucial.
When exposed to air, VH2O2 breaks down into harmless byproducts: water and oxygen. This transformation underscores its reputation as an environmentally friendly disinfectant. Moreover, when vaporized, hydrogen peroxide molecules can penetrate various surfaces effectively. This penetrative ability enhances its capacity to kill microorganisms in hard-to-reach areas, making it an efficient choice for thorough disinfection.
Low-temperature sterilization is perfect for applications involving materials that are sensitive to heat. Certain plastics, electronic components, and other fragile materials that cannot withstand traditional sterilization techniques can be safely treated with vaporized hydrogen peroxide. Some endoscopes on the market today, such as bronchoscopes, cystoscopes and rhinolaryngoscopes, are validated for VH2O2 sterilization.
However, while VH2O2 is recognized for its antimicrobial efficacy and safety in many applications, it has some drawbacks. High concentrations of vaporized hydrogen peroxide can lead to potential skin irritation or respiratory discomfort if inhaled, emphasizing the need for adequate ventilation during application. Proper monitoring protocols are essential to maintain a safe working environment while using this agent. Additionally, VH2O2 can be corrosive to certain materials, limiting its use in specific contexts or requiring careful selection of compatible materials.
Overall, vaporized hydrogen peroxide is a powerful and effective solution for sterilization and decontamination. It combines high efficacy against various microbes with a relatively safe and environmentally benign profile.
Peracetic
Peracetic acid is a powerful liquid sterilant (LCS) utilized with a specialized liquid chemical sterilization system to disinfect heat-sensitive medical devices effectively. In this process, the device is fully immersed in the sterilant, ensuring thorough exposure to eliminate pathogens, and subsequently rinsed to eliminate residual sterilant.
During the rinsing phase, the water is meticulously treated to eradicate or neutralize harmful microorganisms, including bacteria, viruses, protozoa and fungi. This makes the system adept at processing various flexible endoscopes commonly used in multiple medical procedures.
Although this system is classified as a point-of-use sterilizer, it is essential to note that if the disinfected devices are not immediately used and are instead stored after the sterilization cycle, their status changes from sterile to high-level disinfection, which may not ensure complete safety against microbial contamination. The entire sterilization cycle is precisely timed at 30 minutes, utilizing a neutral pH use dilution specially formulated to protect delicate instruments from potential damage. Given the chemicals involved, personnel handling the sterilization must don appropriate personal protective equipment to ensure their safety and minimize exposure risks.
Gas Plasma
Plasma sterilization is an innovative and efficient process designed to eliminate microorganisms from surfaces using the unique properties of gas plasma. This method operates at low temperatures, making it exceptionally suitable for items that are sensitive to heat, such as delicate medical devices, advanced electronics and various agricultural products. The process begins by injecting hydrogen peroxide into a specially designed vacuum chamber. Inside this chamber, the hydrogen peroxide is vaporized, transforming into a gas that thoroughly permeates the enclosed space. Radio-frequency or microwave energy is then applied to create the plasma, causing the hydrogen peroxide gas to ionize and form a reactive plasma state. This plasma is rich in free radicals, which are highly energetic particles capable of damaging the cellular structure of microorganisms, disrupting their vital functions.
As the sterilization process unfolds, the plasma undergoes a transformation and ultimately breaks down into harmless by-products: water and oxygen molecules, both nontoxic and environmentally friendly.
One of the standout features of plasma sterilization is its effectiveness against various microorganisms, including resilient bacteria, stubborn fungi and harmful viruses. Moreover, this method can significantly reduce cycle times compared to traditional sterilization techniques, enhancing efficiency in settings that require rapid turnaround. Plasma sterilization proves invaluable for sanitizing medical instruments, especially those prone to corrosion. This allows for safe, reliable use in critical healthcare applications. Plasma sterilization is a cutting-edge solution for maintaining hygiene and safety in numerous sensitive environments.
Mission Critical
The growing momentum to adopt sterilization protocols for endoscopes is primarily driven by the substantial risk posed by patient-to-patient transmission of infections linked to inadequately disinfected instruments. This concern is particularly acute for endoscopes interacting with mucosal surfaces, such as gastrointestinal scopes that are directly exposed to internal bodily environments. Sterilization techniques provide a markedly enhanced level of decontamination, eliminating nearly all types of microorganisms, including highly resistant spores that can survive standard disinfection processes. These spores can potentially initiate severe infection outbreaks that can have dire consequences for patient health if not addressed through rigorous decontamination practices.
Moreover, the intricate and often sophisticated design of endoscopes— including their narrow lumens, complex moving parts, and multiple channels—presents significant challenges for thorough cleaning and adequate disinfection. This complexity increases the likelihood of residual contamination and emphasizes the necessity for reliable sterilization methods to ensure patient safety and prevent the risk of infection. The shift toward a sterilization approach is essential in addressing these critical concerns and protecting patient well-being.
High-level disinfection (HLD) is widely recognized as the gold standard for reprocessing semi-critical flexible endoscopes. This classification stems from the Spaulding Classification system, which categorizes medical devices based on their risk of infection; according to this system, most flexible endoscopes are designated as semi-critical devices. During diagnostic and therapeutic procedures, these devices make close contact with intact mucous membranes. Still, they typically do not penetrate sterile tissues within the human body, and this factor influences the appropriate level of disinfection required.
Disinfection is a critical process defined as “the method to inactivate viable microorganisms to a level that is considered safe for a specific purpose” (ISO 15883-4:2018). HLD is particularly important in this context, as it ensures that the endoscopes are sufficiently disinfected to prevent infection while maintaining their functionality and integrity.
Despite ongoing discussions surrounding sterilization techniques, there is a lack of substantial evidence demonstrating that sterilization yields significantly better clinical outcomes compared to high-level disinfection. As a result, HLD continues to be the preferred and most widely accepted method for processing flexible endoscopes, balancing efficacy in infection control with practical considerations of device handling and patient safety.
In policy, the Centers for Disease Control and Prevention aligns with the Food and Drug Administration: if a medical device can be sterilized, it should be sterilized. The FDA actively encourages manufacturers to sterilize any device, as proper sterilization is crucial for preventing patient infections and is considered a standard practice for medical devices that come into contact with sterile body tissues or fluids. If the margin of safety is higher with sterilization, the facility should use the method with the highest level of validated reprocessing methods.
The ultimate litmus test is what is best for the patient.
