An endoscope is a flexible, illuminated tube used by physicians to examine internal organs and body cavities, such as the colon, stomach, or lungs. Since these instruments are inserted directly into the patient’s body and contact mucous membranes, they are categorized as semi-critical medical devices that must be meticulously cleaned before reuse. Endoscope reprocessing is the complex, multi-step procedure designed to clean, disinfect, and prepare the device for safe use on the next patient. This rigorous process is necessary to eliminate biological material and microorganisms that could otherwise lead to serious healthcare-associated infections.
Why Reprocessing is Essential for Patient Safety
The unique and intricate design of flexible endoscopes poses a significant challenge to infection control, making thorough reprocessing absolutely necessary for patient safety. These instruments contain long, narrow internal channels for suction, irrigation, and the passage of surgical tools. The complex internal mechanics and the presence of small, difficult-to-access components, such as the elevator mechanism on duodenoscopes, create areas where biological debris can easily collect and dry.
If organic material like blood, tissue, and mucus is not completely removed, it can form a protective layer known as a biofilm. Biofilms shield bacteria, viruses, and spores from the effects of disinfection, allowing dangerous pathogens to survive the cleaning process. The transmission of multi-drug resistant organisms has been linked to inadequately reprocessed endoscopes. Because endoscopes contain heat-sensitive components, they cannot typically withstand the high temperatures of steam sterilization, necessitating a specialized combination of cleaning and High-Level Disinfection (HLD).
The Stages of Endoscope Reprocessing
The reprocessing cycle is a sequential series of steps, where the success of each stage directly influences the effectiveness of the next.
Pre-Cleaning and Leak Testing
The first step is pre-cleaning, which begins immediately at the patient’s bedside after the procedure is complete. This involves wiping the exterior of the insertion tube and flushing the internal channels with a detergent solution to prevent biological soil from drying and adhering to the surfaces. Once transported to the reprocessing area, the endoscope undergoes a leak test. This test pressurizes the instrument with air while it is submerged in water to check for bubbles that would indicate internal or external damage. A damaged endoscope must be removed from circulation, as its channels cannot be effectively disinfected.
Manual Cleaning
Following a successful leak test, the device is subjected to meticulous manual cleaning, which is widely considered the most important step. Technicians use specialized, appropriately sized brushes to physically scrub the interior of all accessible channels and the exterior surfaces. Enzymatic detergent solutions are flushed through the channels to break down protein and fat, ensuring that all physical debris, known as bioburden, is removed. If physical debris remains after manual cleaning, the subsequent disinfection step will fail because the organic material neutralizes the disinfectant.
High-Level Disinfection (HLD)
After manual cleaning and a thorough rinse with clean water, the endoscope moves to High-Level Disinfection (HLD) or sterilization. HLD involves immersing the scope and circulating a liquid chemical germicide, such as glutaraldehyde or hydrogen peroxide, through all channels for a specified contact time and temperature. Automated Endoscope Reprocessors (AERs) are often used to manage this chemical contact phase, standardizing the exposure time and temperature. However, AERs do not replace the necessity of thorough manual cleaning, as they cannot effectively remove adherent physical debris.
Rinsing and Drying
The HLD step is followed by a thorough rinse with sterile or filtered water to remove all traces of the chemical disinfectant, which could otherwise be toxic to the next patient. The final stage is the alcohol flush and drying, which is essential to prevent the growth of waterborne organisms. A solution of 70% to 90% ethyl or isopropyl alcohol is flushed through the channels to displace the water, followed by a purge of filtered, forced air. Complete drying of the interior channels is paramount, as residual moisture can support microbial proliferation during storage.
Verification and Safe Storage Protocols
After the cleaning and disinfection stages are complete, a system of checks and balances verifies the efficacy of the entire reprocessing procedure. The initial verification is a visual inspection of the endoscope’s exterior and internal channels, often performed with magnification tools, to confirm the absence of any remaining debris or damage. Cleaning-verification tests use biochemical indicators to detect residual protein, hemoglobin, or ATP on the surfaces, objectively measuring the cleanliness of the device.
For the HLD step, the chemical concentration of the disinfectant solution is checked using specific test strips before each use. This ensures the germicide is at its minimum effective concentration, guaranteeing its ability to inactivate microorganisms. Documentation of these verification steps creates an auditable record for every reprocessed endoscope.
The final step before reuse is proper storage, which is necessary to maintain the disinfected state of the instrument. Endoscopes must be stored vertically in specialized drying cabinets that circulate filtered air. Hanging the scopes vertically facilitates drainage and continuous drying, which maintains the integrity of the reprocessing work. Institutions must also establish a maximum safe storage period, sometimes called “hang time,” after which the endoscope must be reprocessed again before it can be used on a patient.