Do EWDs/AERs Dry Endoscopes at the End of the Reprocessing Cycle?

Published on:

September 3, 2025

Last updated on:

December 16, 2025

• Expert Q&A

Question:

Do EWDs/AERs dry endoscopes at the end of the reprocessing cycle?

Answer:

This depends on the endoscope washer-disinfector (EWD)/ automated endoscope reprocessor (AER) available in your region of the world, and in use at your facility!

In the US, automated endoscope reprocessors (AERs) are generally not programmed to perform drying of an endoscope at the completion of a reprocessing cycle. This means that at the end of an AER reprocessing cycle, the endoscope will still have visible moisture. US-based AERs often complete their reprocessing cycle with three steps: 1) a final rinse water flush, 2) an alcohol flush, and finally 3) an air purge. An air purge is a short duration of air flushed through the endoscope to aid in the dispersal of large amounts of residual fluid inside the endoscope. This contrasts with drying, which is a prolonged process (generally 10-minutes or longer) intended to remove all moisture from an endoscope’s internal and external surfaces. Some literature has confused the role of air purge vs. drying in the removal of moisture from an endoscope, and has been misguided in their claims that endoscopes should be dry upon removal from an AER ^{[1 - 3]}. In the US, end-users should anticipate that an endoscope reprocessed in an AER will be visibly moist at the end of the cycle and should proceed with a drying process outside of the AER.

In Europe and other regions outside the US, in accordance with ISO 1588-4, EWDs include a standard “short” drying program – an air purge to remove most of the residual fluid from the channels – and some also include a validated “long” drying program that will provide end-users with a dry endoscope at the completion of the reprocessing cycle ^[4]. Only the “long” drying programs ensure complete removal of moisture in all channels and outer surfaces of the endoscope. Due to the duration of the “long” drying programs, these programs are generally only used at the end of the working day. In most cases, the EWD standard “short” program with the air purge is used in daily practice, either because the reprocessed endoscope is intended for immediate clinical use or storage is performed in a dedicated drying/storage cabinet compliant with EN 16442 ^[5]. The endoscope preconditioning provided by the air purge in the standard “short” program is important because not all drying/storage cabinets are able to dry completely wet endoscopes in a reasonable period of time.

The takeaway? Air purge and drying are not interchangeable terms and do not provide the same end result. End-users should understand whether their EWD/AER will perform an air purge, resulting in a visibly moist endoscope that needs to be dried, or if their EWD/AER has a validated drying program that will provide them with a dry endoscope directly from the basin.