Sterilization

Purpose

This document provides guidance for sterilizing reusable medical devices to be used in perioperative and procedural settings. Items that enter sterile tissue, including the vascular system, are categorized as critical using the Spaulding classification and should be sterile when used.¹  An important factor in preventing surgical site infections (SSIs) is the use of only sterile instruments and medical devices for operative and other invasive procedures. Surgical site infections are among the most common health care–associated infections, comprising 31% of all health care–associated infections among hospitalized patients.²  Between 2006 and 2009, SSIs complicated an estimated 1.9% of surgical procedures in the United States.³  The Centers for Disease Control and Prevention (CDC) health care–associated infection prevalence survey found there were an estimated 157,500 SSIs associated with inpatient surgeries in 2011.² 

Surgical site infections may cause serious injury or death at enormous cost to patients, their families, and the health care organization. A systematic review of the literature on SSI from 1998 to 2014 found the estimated average cost of an SSI ranged between $10,433 (2005 dollars) and $25,546 (2002 dollars),³  which equates to approximately $13,300 to $35,400 in 2018 dollars. Costs can exceed $90,000 per infection when the SSI involves a prosthetic joint implant or an antimicrobial-resistant organism.³ 

Sterility is accomplished through a multistep process. This process begins immediately after instrument use with the removal of gross soil, followed by further cleaning, decontamination, inspection, packaging, and finally sterilization. Each step is critical in producing sterile items and maintaining sterility until the item is opened and delivered to the sterile field for use. Effective sterilization cannot take place without effective cleaning, decontamination, and packaging. Substances such as bioburden, biofilm, plaques, soils, and oils inhibit sterilization. The degree to which sterilization is inhibited is correlated with the amount, number, type, and inherent resistance of these substances. Any of these substances may shield microorganisms on items from contact with the sterilant or combine with and inactivate the sterilant. Sterile barrier packaging increases the probability that sterility will be achieved and maintained until the package is opened at the point of use.

Sterility may be achieved by a variety of physical or chemical processes. The selection of the sterilization method is dependent on a number of factors including device design, material, packaging, compatibility with the sterilant, load limitations, safety requirements, and organization-specific considerations. The most common sterilization methods used in health care in the United States are addressed in this guideline. New sterilization technologies are being developed and may become commercially available in the future but are not yet cleared by the US Food and Drug Administration (FDA) for use in the United States. This document provides guidance only for sterilization processes commonly used in health care and currently cleared by the FDA.

The guideline addresses

• saturated steam under pressure;

• ethylene oxide;

• low-temperature hydrogen peroxide gas plasma;

• low-temperature hydrogen peroxide vapor;

• ozone combined with hydrogen peroxide;

• dry heat;

• liquid chemical sterilization using peracetic acid;

• loading the sterilizer and load configuration;

• transport of sterile items;

• quality control measures; and

• installation, care, and maintenance of sterilization equipment.

Guidance for the following topics is outside of the scope of this document:

• specific guidance for reprocessing of medical devices labeled as single use, criteria for evaluating the services of a third-party reprocessor, and identifying single-use items for reprocessing;

• cleaning and decontamination of surgical instruments;

• high-level disinfection;

• packaging;

• loaned instruments;

• facility design;

• sterilization processes not cleared by the FDA for use in health care facilities (eg, gamma or electron beam radiation, chlorine dioxide, nitrogen dioxide);

• processing of medical devices that have been or potentially have been exposed to prions; and

• cost comparison and analysis of various methodologies.

The reader should refer to the AORN Guideline for Cleaning and Care of Surgical Instruments,⁴  Guideline for Manual Chemical High-Level Disinfection,⁵  Guideline for Flexible Endoscopes,⁶  Guideline for Selection and Use of Packaging Systems for Sterilization,⁷  and Guideline for Design and Maintenance of the Surgical Suite⁸  for guidance on these important topics related to the sterilization process.

Evidence Review

A medical librarian conducted a systematic search of the databases Ovid MEDLINE®, EBSCO CINAHL®, Scopus®, and the Cochrane Database of Systematic Reviews. The search was limited to literature published in English from January 2012 through December 2017. At the time of the initial search, weekly alerts were created on the topics included in that search. Results from these alerts were provided to the lead author until February 2018. The lead author requested additional articles that either did not fit the original search criteria or were discovered during the evidence appraisal process. The lead author and the medical librarian also identified relevant guidelines from government agencies, professional organizations, and standards-setting bodies.

Search terms included autoclave, biofilms, biological indicators, biomaterial, burns, central services department, chemical indicators, clinical quality measures, disinfectant agent, dry heat, dynamic air cycles, ethylene oxide, flash sterilization, gravity displacement, hydrogen peroxide, hydrogen peroxide gas, hydrogen peroxide gas plasma, immediate use, immediate use flash sterilization, immediate use steam sterilization, indicators and reagents, installation qualification, instrument processing, instrument sterilization, IUSS, liquid chemical sterilants, load release, loading sterilizer, Medivators, mixed loads, moist heat, operational qualification, ozone, peracetic acid, performance qualification, prevacuum, process challenge, quality assurance testing, reagent strips, satellite processing, steam, steam flush pressure pulse, sterile processing department, sterility assurance levels, sterilization, sterilization and disinfection, sterilization cycles, sterilization efficacy, sterilization modalities, sterilization monitoring, sterilization parameters, sterilization quality, sterilizer load configuration, sterilizer load weight limit, Steris, Sterrad, surgical equipment, surgical instruments/microbiology, tabletop sterilizer, user validation, vacuum sterilizer, vaporized hydrogen peroxide, wet heat, and wet instrument trays.

Included were research and non-research literature in English, complete publications, and publications with dates within the time restriction when available. Excluded were non-peer-reviewed publications and older evidence within the time restriction when more recent evidence was available. Editorials, news items, and other brief items were excluded. Low-quality evidence was excluded when higher-quality evidence was available, and literature outside the time restriction was excluded when literature within the time restriction was available (Figure 1).

Figure 1

Flow Diagram of Literature Search Results

Adapted from: Moher D, Liberati A, Tetzlaff J, Atman DG; The PRISMA Group. Preferred reporting items for systematic reviews and meta-analyses: The PRISMA Statement. PLoS Med. 2009;6(6):el000097.

Articles identified in the search were provided to the project team for evaluation. The team consisted of the lead author, a coauthor, and two evidence appraisers. The lead author divided the search results into topics and assigned members of the team to review and critically appraise each article using the AORN Research or Non-Research Evidence Appraisal Tools as appropriate. The literature was independently evaluated and appraised according to the strength and quality of the evidence. Each article was then assigned an appraisal score. The appraisal score is noted in brackets after each reference as applicable.

Each recommendation rating is based on a synthesis of the collective evidence, a benefit-harm assessment, and consideration of resource use. The strength of the recommendation was determined using the AORN Evidence Rating Model and the quality and consistency of the evidence supporting a recommendation. The recommendation strength rating is noted in brackets after each recommendation.

Note: The evidence summary table is available at http://www.aorn.org/evidencetables/.

Editor’s note: MEDLINE is a registered trademark of the US National Library of Medicine’s Medical Literature Analysis and Retrieval System, Bethesda, MD. CINAHL, Cumulative Index to Nursing and Allied Health Literature, is a registered trademark of EBSCO Industries, Birmingham, AL. Scopus is a registered trademark of Elsevier B.V., Amsterdam, The Netherlands. Sterrad is a registered trademark of Johnson & Johnson, New Brunswick, NJ.