# A Shelf-Life Assessment of Sterilized Surgical Instruments Stored Under Controlled Conditions: A Comparative Study of a Single vs. Double Self-Sealing Pouch

## TL;DR

This study compared the shelf life of sterilized surgical screws in single and double self-sealing pouches, finding that both maintained sterility for 182 days, but one single-pouch screw became contaminated after 390 days.

## Contribution

The study provides new empirical evidence on the time-dependent sterility risk of single-pouch packaging for surgical instruments.

## Key findings

- No bacterial growth was detected in either single or double pouches up to 182 days.
- After 390 days, one screw in the single-pouch group showed bacterial contamination.
- No statistical difference was found between the two groups, but the result suggests a need for time-based sterility studies.

## Abstract

Postoperative infections are a common concern in small-animal surgery, and the proper sterilization of surgical instruments is essential to prevent them. This study evaluated the shelf life of sterile surgical screws stored under controlled environmental conditions at the Veterinary Teaching Hospital of Naples. We compared two packaging methods, namely single and double self-sealing pouches, over 390 days. While no bacterial growth was detected in either group up to 182 days, after 390 days, one screw in the single-pouch group showed bacterial contamination. While current guidelines focus on event-related contamination, this outcome reveals a low-level, time-dependent threat to sterility. These findings emphasize the need for future time-based studies and further evaluation of packaging methods to ensure sterility.

(1) Background: postoperative surgical-site infections are a significant complication in small-animal surgical procedures, with detected rates ranging from 0.8% to 18.1%, depending on the type of surgery. The sterilization process of surgical instruments is a crucial factor in infection control, but the shelf life of surgical instruments and the best packaging method are not precisely defined due to the multiple variables that influence them. This study aimed to assess the shelf life of surgical instruments stored under controlled environmental conditions in a veterinary hospital and compare two packaging methods: using a self-sealing single pouch versus a self-sealing double pouch. (2) Methods: a sample of 400 non-sterile screws was divided into three groups: Group 1 (175 screws in single pouches), Group 2 (175 screws in double pouches), and Group 3 (50 non-sterile screws as a control group to verify the microbial culture efficiency). Microbiological tests were conducted at 1, 7, 15, 30, 60, 182, and 390 days post-sterilization. (3) Results: no bacterial growth was detected on screws packaged in single and double pouches up to 182 days. However, after 390 days, bacterial growth was observed in one screw packaged in a single pouch. In Group 3, only two screws turned out to be bacteriologically positive. (4) Conclusions: no statistical difference was found between the two groups; however, the detection of a single positive screw in the single-pouch group raised a potential clinical consideration, suggesting the need for further studies based on events and time.