Process Failures, Wet Packs and Recalls

Understanding Wet Packs and Moisture Prevention

A wet pack is defined as any package containing moisture on its exterior surface or inside the pack after cooling. Moisture on or inside a sterile package compromises packaging integrity and creates a pathway for microbial migration through a process called wicking. Wicking is the transfer of microorganisms through wet packaging materials by capillary action. Because capillary action allows microscopic contaminants to travel directly through the packaging material, any package confirmed to be a wet pack must be considered non-sterile and completely reprocessed.

Wet packs often stem from issues within the steam delivery and sterilizer drainage systems. Poor-quality steam containing excess moisture, including steam affected by boiler or distribution-system problems, directly contributes to wet packs. Within the sterilizer chamber, a clogged or dirty chamber drain strainer impedes steam condensate drainage, promoting water pooling. Operational programming also plays a critical role, as selecting or programming an insufficient drying time in the sterilizer cycle causes moisture to remain trapped inside the packages.

Environmental conditions and handling practices during cooling are just as critical as cycle parameters. Placing warm, freshly sterilized packs onto cold metal shelves creates rapid condensation, resulting in wet packs. Similarly, unloading a sterilizer cart directly under active air conditioning vents accelerates condensation and produces wet packs. Sterilized items must remain undisturbed on the sterilizer cart until they reach ambient room temperature. Technicians must avoid handling warm packages, because handling items before they cool contributes to both condensation and contamination.

Technicians must also prevent moisture through proper instrument assembly and loading techniques. Nesting solid metal basins without an absorbent separator, when an absorbent separator is required by the manufacturers' instructions for use, traps condensate between the basin walls. Wrapping sets too tightly or using excess wrapping material restricts steam penetration and prevents moisture evacuation during drying. Additionally, exceeding maximum instrument set weight limits increases thermal mass and can cause excessive condensation. Non-absorbent tray liners or dense silicone mats can pool condensate if they are not used according to the manufacturer's instructions for use. Finally, overloading sterilizer carts inhibits proper steam circulation and prevents efficient drying, while peel pouches must be positioned as directed by the pouch and sterilizer manufacturers' instructions for use, using appropriate racks when required and avoiding arrangements that trap moisture.

Whenever a wet pack is identified, the technician must inspect all packages from the same sterilizer load for moisture, including packages that have already been removed from the cart. If multiple wet packs are discovered in that same load, the entire load must be treated as non-sterile and reprocessed.