How Do I Know It's Sterile?


Sterilization of reusable medical devices is a great thing to prevent patient infection, but how do we know a medical device is sterile? Well, the sterility of medical devices cannot be directly verified prior to clinical use. For this reason, sterilization processes themselves must be validated. The goal of this validation is to confirm the success and repeatability of the sterilization process when performed within validated parameters. These include microbial loads, types of devices, load configurations, sterile packaging, load temperature, etc. In addition to this validation, users routinely monitor the sterilization process by confirming adequate sterilizer cycle parameters (e.g. pressure, time, H2O2 concentration) and by using process indicators (BI, CI, PCD). Does this all guarantee that we get sterile devices? Not exactly. Sterility is not an absolute certainty; it is a probability. A sterilization process reduces the number of viable microorganisms on medical devices. We can even measure it! For H2O2 sterilization, this is typically measured in a laboratory by using half of the sterilization cycle, while employing operating conditions that are deemed the most challenging. These test conditions reflect the validated process parameters. The measured reduction of microorganisms at half-cycle can be used to calculate the odds of getting a non-sterile device with the full cycle. The FDA requirement is that no more than one in a million devices sterilized may have a viable microorganism remaining. This specific threshold corresponds to the Sterility Assurance Level (SAL) of 10-6! To consistently achieve this sterility assurance level during routine sterilization, it is essential that medical devices are processed within the validated limits and according to the indications provided by the manufacturers of all devices involved: the medical devices being sterilized, the sterilizer, the sterile packaging, the process indicators. In other words, to prevent patient infection… follow the IFUs!