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Immediate-Use Steam Sterilization Happens in a Flash

What constitutes best practice when it comes to immediate-use steam sterilization (IUSS)?

Immediate-use steam sterilization, formerly called flash sterilization, is described as “the shortest possible time from the item being removed from the sterilizer to the aseptic transfer onto the sterile field.”1 These items are not intended to be stored for future use. We must take into consideration all the guidelines and rules that support this method of sterilization that is often overused in our industry. The ultimate goal for all of us in the healthcare industry is to prevent healthcare-associated infections (HAIs) and surgical site infections, and to keep our patients safe. In this article, we will cover when the name changed, the three documents needed to thoroughly identify safety needs, how the standards came to be, and how to calculate IUSS in your own facility.

The name changes from flash sterilization to IUSS
The term flash sterilization changed over the years, and we still hear it used occasionally in our industry. In 2011, a position paper was issued according to Centers for Medicare & Medicaid Services (CMS).2

At that time, the Association for the Advancement of Medical Instrumentation (AAMI) hosted a summit meeting on flash sterilization. Invitations to the summit included professional organizations, regulatory agencies, and accreditation organizations. Several organizations thought that the term “flash sterilization” was misleading; therefore, the group agreed to use the term immediate-use steam sterilization (IUSS).2

By the end of the meeting, a consensus document titled “Immediate-Use Steam Sterilization” was drafted as an industry effort to clarify and improve the practice of flash sterilization. They determined in this position paper that “‘flash sterilization’ is an antiquated term that does not fully describe the various steam sterilization cycles now used to process items not intended to be stored for later use. Current guidelines may require longer exposure times and/or the use of single wrappers or containers designed to allow for aseptic transfer of an item to the point of use. The term ‘immediate-use steam sterilization’ more accurately reflects the current use of these processes.”3

Reprocessing policies have to be standardized and routinely practiced to achieve any great outcome. Would you agree? Let’s do a bit of deep dive to understand them. 

The three documents needed to thoroughly identify safety
Three main documents exist that every infection preventionist (IP), operating room (OR), and sterile processing professional should have access to:

  • AAMI’s ANSI/AAMI ST79: Comprehensive guide to steam sterilization and sterility assurance in health care facilities
  • AORN’s Perioperative Standards and Recommended Practices
  • CDC’s Guideline for Decontamination and Sterilization in Healthcare Facilities (2008)4

How the standards came to be
Getting to the ANSI/AAMI ST79 standards was no joke, and quite the feat combining five documents into one. From 2006 to now, this has had three revisions, each revision with amendments. Wow! That was a mouthful, and I get tired just typing it, let alone digesting how to put them into practice.

The first edition of ST79 was published in 2006, and it combined the five documents into a single publication:

  • ANSI/AAMI ST46 Steam Sterilization and Sterility Assurance in Healthcare Facilities
  • ANSI/AAMI ST42 Steam Sterilization & Sterility Assurance Using Table-Top Sterilizers in Office-Based, Ambulatory Care, Medical, Surgical, and Dental Facilities
  • ANSI/AAMI ST37 Flash Sterilization—Steam Sterilization of Patient Care Items for Immediate Use
  • ANSI/AAMI ST35 Safe Handling and Biological Decontamination of Reusable Medical Devices in Health Care Facilities and in Non-Clinical Settings
  • ANSI/AAMI ST33 Guidelines for the Selection and Use of Reusable Rigid Container Systems for Ethylene Oxide Sterilization and Steam Sterilization in Health Care Facilities4

From the American Journal of Infection Control, “In 2008 and 2009, numerous amendments of the document were adopted as part of the AAMI continuous maintenance process….The second edition of ST79 was published in 2010 and includes changes in the requirements regarding steam quality, paper-plastic pouches, mechanical cleaning equipment, product quality assurance testing (with respect to product families), and risk analysis. An amendment adopted in 2010 provides additional information about Class 6 chemical indicators and provides a new section on New Product Evaluation.” Then came ST79:2010/A3:2012, which standardized the usage.4

All the red tape and standards, revisions to standards, and entity summits should paint a clear picture for us all as to the severity of IUSS being used correctly and when necessary.

Calculating IUSS in your facility
Finally, let’s take a look at how we calculate IUSS rates in our own facilities. In the American Journal of Infection Control, Volume 41, Issue 5, Supplement, May 2013, pages S46–S48, Rose Seavey gives us information on calculating IUSS rates (see image below), and it’s the total number of IUSS cycles per month divided by the total number of cases per month.4

From my personal insights and experience in sterile processing, it’s important to keep in mind the types of instruments and procedures, and the specific surgeons whose procedures require an increase in the amount of IUSS. Identifying trends will tell us a story that either we need to reassess our inventory, our scheduling, or the number of consignment vendor trays on hand.

The moral of the story is that IUSS is steam sterilization intended for immediate use; nevertheless, sterilization cannot be done in a flash. If monitored correctly, the actual sterilization process is just as efficacious as terminal sterilization; however, the real issue is how the devices are handled before and after sterilization. As with all sterilization processes, the manufacturers’ written validated instructions for use must be precisely followed.


  1. Jointcommission.org. “Instrument Reprocessing—Immediate Use Steam Sterilization (IUSS): What are important considerations associated with Immediate-Use Steam Sterilization?” Last updated March 3, 2021, accessed July 26, 2021. https://www.jointcommission.org/standards/standard-faqs/critical-access-hospital/infection-prevention-and-control-ic/000002122/
  2. CMS.gov. “Change in Terminology and Update of Survey and Certification (S&C) Memorandum 09-55 Regarding Immediate Use Steam Sterilization (IUSS) in Surgical Settings,” memorandum, August 29, 2014. https://www.cms.gov/Medicare/Provider-Enrollment-and-Certification/SurveyCertificationGenInfo/Downloads/Survey-and-Cert-Letter-14-44.pdf
  3. “Immediate-Use Steam Sterilization,” accessed July 26, 2021. http://s3.amazonaws.com/rdcms-aami/files/production/public/FileDownloads/Products/ST79_Immediate_Use_Statement.pdf
  4. Seavey, Rose, MBA, BS, RN, CNOR, CRCST, CSPDT, “Immediate use steam sterilization: Moving beyond current policy.” American Journal of Infection Control, Volume 41, Issue 5, Supplement, pp. S46–S48. https://www.ajicjournal.org/article/S0196-6553(13)00006-0/fulltext#back-bib3

Rebecca Kinney is a medical sales representative and small business owner of Cypress, Inc. She is a Certified Central Service Vendor Partner (CCSVP). Rebecca has worked in healthcare for more than 15 years: 7 years as a sterile processing technician and 8 years in medical sales working directly with SP. Focused on a proactive and consultative approach, she takes her experience to share knowledge in the field she wishes she knew when she worked in SP. She actively participates in speaking engagements and uses LinkedIn as an educational tool to reach an audience of almost 30,000 professionals. 

Continual process improvement and education lending to patient safety has always been her primary objective.

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