November 26, 2025 (by: Lawrence F Muscarella, PhD) – Earlier this month, Dr. Muscarella published an in-depth review — the first in a series of two articles — of the newly released “Multisociety guidance for sterilization and high-level disinfection.”
Issued in April and endorsed by several organizations—including the Joint Commission—this 2025 multisociety guidance “follows” the Centers for Disease Control and Prevention’s 2008 “Guideline for Disinfection and Sterilization in Healthcare Facilities.”
Whereas Dr. Muscarella’s first article focused on sheathed semicrticial devices and endoscope-related Pseudomonas infections, this supplemental article — the second in this series of two — provides a position statement promoting aseptic techniques in operating rooms while also comparing Dr. Muscarella’s advice on the use of immediate use steam sterilization to the multisociety’s guidance on IUSS.
This supplemental article may provide the most comprehensive review and guidance published to date on the use of IUSS in operating room settings.
(Dr. Muscarella is the founder and president of LFM Healthcare Solutions, LLC. This article is a draft and may be subject to changes and revisions without further notice.)
Accepting new clients: Dr. Muscarella is accepting new clients seeking expert guidance in infection prevention, the causes and prevention of healthcare-associated infections and other medical errors; disinfection and sterilization; and other related topics.
HIGHLIGHTS
- Earlier this month, Dr. Muscarella published an in-depth review—the first in a series of two articles—of the newly released document titled “Multisociety guidance for sterilization and high-level disinfection.”
- Issued in April and endorsed by several organizations—including the Joint Commission—this multisociety document “follows” the Centers for Disease Control and Prevention’s 2008 “Guideline for Disinfection and Sterilization in Healthcare Facilities.”
- While Dr. Muscarella’s earlier review of this 2025 guidance document focused on several infection prevention strategies, this supplemental article—the second in this series of two articles—provides a position statement promoting safety and aseptic techniques in operating rooms while also comparing some of its advice to the multisociety’s guidance on the use of immediate use steam sterilization — “IUSS” — to process surgical devices and implants.
- For example, Dr. Muscarella advises that IUSS may be performed for surgical instruments but only as an exception and in a defined “emergency situation.” Further, he advises against the use of IUSS for implantable devices due to this rapid sterilization process’s increased risk for errors and serious surgical site infections, as the CDC has published.
- However, if IUSS is deemed absolutely necessary by authorized staff members to process an implant in an exceptional, rare and documented emergency, this supplemental article advises that certain criteria be met and information recorded, including the IUSS cycle data and the name (and signature) of the surgeon or individual who approved IUSS’s use.
- This article by Dr. Muscarella instructs — possibly for the first time — that the use of IUSS to process a surgical instrument, particularly and especially an implantable device, be recorded in the patient’s chart, disclosed, and documented as part of the patient’s permanent medical record to promote transparency and accountability in healthcare, advance a culture of safety, and eliminate preventable harms including surgical site infections.
- This article may provide the most comprehensive review and guidance published to date on the use of IUSS to process surgical devices used in operating room settings.
November 26, 2025 (by: Lawrence F Muscarella, PhD) – Several societies and organizations, including The Joint Commission, jointly issued new guidance, in April, for the disinfection and sterilization of reusable medical instruments, including flexible endoscopes.
This endorsed 2025 document — titled “Multisociety guidance for sterilization and high-level disinfection” — provides guidance that “follows” the Centers for Disease Control and Prevention’s “Guideline for Disinfection and Sterilization in Healthcare Facilities” published in 2008.
Like this 2008 CDC guideline, for example, the new multisociety guidance document discusses: (a) Spaulding’s classification scheme for categorizing medical devices based on the infection risk; (b) covering a reusable semi-critical medical device with a single-use sheath (or probe cover) to prevent contamination and cross-infections; and (c) the use of immediate use steam sterilization (IUSS), among other timely topics.
Presented as questions to which recommendations are provided in response, many of the 2025 multisociety document’s strategies to prevent healthcare-associated infections are reasonable, practical and well referenced.
Forensic Case Reviews, Expert Guidance, Infection Investigations: LFM-Healthcare Solutions, LLC provides medical expertise for legal representatives, device manufacturers, and medical facilities specializing in healthcare-associated infections linked to contaminated reusable medical equipment.
Immediate use steam sterilization (IUSS)
Some of the multisociety’s 2025 other guidance, however, Dr. Muscarella found to be confusing and to raise questions and concerns for him about he potential for variations in clinical practices, different standards of care, and the risk of infections in endoscopic and operating room settings.*
By way of an example, the newly endorsed multisociety guidance advises that facilities “not routinely use” immediate use steam sterilization.
While such advice is not entirely uncommon or unique to this 2025 guidance document, it can (unintentionally) facilitate confusion, differing interpretations (e.g., due to inadvertent confirmation bias) of the meaning of “routine” (or “to minimize” the use of IUSS as the Joint Commission has stated), and therefore inconsistent practices in operating room settings — unless the terms are clearly defined in the guidance.
As rationale for its guidance to “not routinely use” IUSS, the 2025 multisociety document asserts that certain conditions and constraints often associated with IUSS “can result in pressure on operating room HCP (healthcare personnel) to eliminate or modify one or more steps prior to sterilization, increasing the risk for errors.”
Other guidance may move one step further, focusing on IUSS’s increased potential for surgical site infections, or “SSIs.”
This article may provide the most comprehensive review and guidance published to date on the use of IUSS. — Lawrence F. Muscarella, Ph.D.
Despite the increased risks to patients, the jointly-endorsed 2025 guidance states that IUSS “is an effective method of sterilization when properly performed” and “can produce a sterile medical device.”
While these claims are similar to the CDC’s 2008 guideline’s assertion that IUSS “is considered acceptable for processing cleaned patient-care items that cannot be packaged, sterilized, and stored before use,” such assessments about IUSS’s safety, quality and performance can raise questions when they are read alongside the urgings of other published guidelines that restrict, or altogether contraindicate, the use of IUSS, particularly for implantable devices due to, as the CDC has acknowledged, “the potential for serious infections.”
The Veterans Health Administration (VHA), for example — like the guidance, policies and procedures, and standards of certain other healthcare organizations, groups, and medical facilities — explicitly restricts the use of IUSS “only in an emergency when there is insufficient time to process by the preferred wrapped or container method.”
As rationale, this VHA directive states that evidence suggests a direct relationship between IUSS and infections.
IUSS must be used only in an emergency when there is insufficient time to process by the preferred wrapped or container method. — The Veterans Health Administration, U.S. Department of Veterans Affairs
Adopting a similar policy that had also previously been the norm in the U.S., a Canadian standard limits IUSS only to “emergency situations” — a term that can also facilitate confusion and inconsistent practices in operating room settings, however, unless it is clearly defined in the guidance.
Whereas one specific facility or healthcare group may define “emergent” in the context of IUSS as “a clinical situation in which any delay incurred places the patient at risk of imminent harm to life, or serious threat to health” (or, similarly, as “a situation where life, limb, or function is at risk“), another organization may instead describe an emergency (for which IUSS might be considered permissible) using examples, such as: (i) when “a non-replaceable instrument has been contaminated and needs to be replaced to the sterile field immediately,” or (ii) when “an item has dropped on the floor and is needed to continue a surgical procedure.”
In spite of these salient differences in published guidance, virtually all guidelines sternly prohibit the use of IUSS:
- for the sake of convenience or to save time
- as a substitute for low instrument inventory (e.g., due to cost considerations)
- insufficient staffing in the sterile processing department, and/or
- in response to observing bioburden on instrument trays in the operating room.
Like the VHA’s rationale for restricting IUSS’s use, the Centers for Medicare & Medicaid Services (CMS) report that practices associated with IUSS “have been implicated in surgical site infections and are considered to pose an increased risk of complications because of potential barriers to thorough completion of all necessary reprocessing steps.”
Consistent with the VHA and CMS’s assessment of IUSS’s infection risks, a study published last year analyzing the risk of surgical site infections identified “a 1.52 times higher risk of SSI following IUSS device reprocessing and significantly increased procedure-specific risk for transplant and plastic surgeries” (although one study reported no statistically significant infection rate differences.)
Another study published two months ago identified an association between a reduction in the use of IUSS during hip and knee surgeries and a statistically significant decrease in SSIs.
This article’s citation: Muscarella LF. Immediate use steam sterilization (IUSS): Dr. Muscarella’s Recommendations and Position Statement. Discussions in Infection Control November 25, 2025.
IUSS for implantable devices?
For some guidelines, use of IUSS to process surgical implants is a particular concern.
The CDC’s 2008 guideline, due primarily to its acknowledgment of the “potential for serious infections,” states that flash sterilization (that is, IUSS) “is not recommended for implantable devices” (though that guideline concedes that IUSS may be unavoidable for some types of devices, such as an orthopedic screw or plate).
Because of the potential for serious infections, flash sterilization (IUSS) is not recommended for implantable devices. — The CDC (2008)
The VHA’s instruction is even stricter, emphasizing that (non-biological) “implantable devices are not to be sterilized by IUSS.” Similarly, the previously noted Canadian standard stresses that IUSS “shall not be used to sterilize implants or complete instrument sets.”
These contraindications notwithstanding, the 2025 multisociety guidance does not advise against using IUSS to process implantable devices. Nor do the policies and procedures of some independent U.S. medical facilities (not within the VHA) contraindicate its use for implants.
Rather, the 2025 document states that IUSS may be used for implants and devices provided certain criteria are satisfied — for example, only when “the devices or implants are heat-stable” and when the manufacturer’s instructions for use (MIFU) provides specific directions for IUSS.
As rationale for its guidance on IUSS, the jointly-issued 2025 multisociety document advises that “IUSS is effective when devices or implants are properly cleaned prior to IUSS, appropriate temperature, pressure, and exposure times are met, and adequate drying and cooling occurs.”
Infection Case Reviews, Forensic Analyses, Expert Guidance: LFM-Healthcare Solutions, LLC provides medical expertise for legal representatives, device manufacturers, and medical facilities specializing in healthcare-associated infections linked to contaminated reusable medical equipment.
Wet surgical instruments can pose an infection risk
The 2025 guidance discusses another practice, or terminal step, involving IUSS that raises additional questions of safety for Dr. Muscarella.
While emphasizing on the one hand that proper controls be maintained “to prevent contamination of the device or implant during removal from the sterilizer and transfer to the sterile field,” the multisociety document discusses on the other hand consideration of a terminal practice after IUSS that could potentially result (inadvertently) in the device’s contamination with exogenous microorganisms just prior to the device’s introduction into the sterile field.
Namely, due to the potential for the hot, flashed surgical device or implant to cause patient burns (understanding that the shorter IUSS cycle has minimal or no drying phase following sterilization), the 2025 guidance document advises as a preventative step or measure “either air-cooling the instruments or immersion in sterile water.”
I advise caution whenever using IUSS to process an instrument, particularly a surgical implant — and even more so if immersion of a hot, flashed implant into a “sterile” solutions or water following IUSS is anticipated to cool the device prior to its immediate introduction into the sterile field. — Lawrence F. Muscarella, Ph.D.
Such guidance for cooling a hot, flashed instrument is not unique, however. One hospital’s on-line standard operating procedure for IUSS advises that devices processed by IUSS “are still hot when received by scrub nurse. Be sure to cool items before passing to surgeon, sterile water on field may be used.”
Similarly, CMS states in a 2014 memorandum that the instrument or item “may be cooled aseptically in cold sterile water” after IUSS and immediately prior to use.
Nevertheless, while this terminal cooling step seems pragmatic on its face, it raises questions about safety, violations of aseptic technique, and whether this workaround measure solves a problem or, instead, potentially introduces a new potentially serious infection risk, particularly when the item processed using IUSS is a surgical implant.*
Published clinical evidence indicates that the clinical use of wet or moist surgical instruments can increase the risk of bacterial contamination and patient infections. Several organizations and agencies have discussed this specific risk:
- CMS memorandum: CMS advised in this same 2014 memo that IUSS is associated with “an increased risk of inadvertent contamination during transfer” of the device to the sterile field, as well as “risks related to wet instruments and the potential for burns.”
- 2025 multisociety guidance: The 2025 multisociety guidance acknowledges that “residual moisture poses a risk to patients by supporting microbial growth.”
- CDC policy: The CDC’s 2008 guideline states that “[s]terile items that become wet are considered contaminated because moisture brings with it microorganisms from the air and surfaces.”
- FDA instruction: An FDA warning letter in 2019 affirms that “[r]etained moisture, also called ‘wet loads,’ following terminal steam sterilization may be viewed as sterilization process failures.”
Whether the Joint Commission, which conducts accreditation surveys of U.S. medical facilities, has adequately considered the risk of serious surgical site infections associated with the use of IUSS to process implants, in general, and this terminal cooling step to prevent clinical burns, in particular, is unclear, its endorsement of the 2025 multisociety guidance and IUSS stance notwithstanding.
Due to this published risk of bacterial infections (and potential legal exposure), this article recommends caution whenever considering IUSS, particularly to process an implantable device — and even more so, if the terminal immersion of a hot, flashed surgical implant into a cooling solution (e.g., cold “sterile” water) is anticipated following IUSS and immediately prior to use.*
Failure to dry the disinfected endoscope properly following the terminal water rinse has been linked to true outbreaks of waterborne bacteria. — Nelson and Muscarella (2006)
Even use of wet, semi-critical endoscopic instruments much less invasive than critical surgical implants has been directly linked to infections, sometimes causally related, with associated morbidity and mortality.
Reports including a review by Nelson and Muscarella (2006) describe multiple cases documenting an association, and in some cases a causal relationship, between patient exposure to wet (or improperly dried) flexible endoscopes, including gastrointestinal endoscopes, and outbreaks of waterborne microorganisms (e.g., Pseudomonas aeruginosa), with significant patient morbidity and mortality.
For several of the cases they reviewed, Nelson and Muscarella (2006) found that the outbreaks (which included pseudo-outbreaks) were abruptly terminated following the implementation of endoscope drying.
Failure to dry the disinfected flexible endoscope terminally, Nelson and Muscarella (2006) emphasized, “can render the reprocessing procedure invalid and clinical use of the endoscope an infection risk.” The two researchers concluded in the same review that the “contribution of post-processing in general and drying in particular” to the prevention of endoscope-related bacterial infections “cannot be overstated.”
Forensic Case Reviews, Expert Guidance, Infection Investigations: LFM-Healthcare Solutions, LLC provides medical expertise for legal representatives, device manufacturers, and medical facilities specializing in healthcare-associated infections linked to contaminated reusable medical equipment.
Position statement — IUSS
Caution is advised whenever considering IUSS, particularly to process an implantable device — and even more so, if the terminal immersion of a hot, flashed implant into a cooling solution (e.g., “sterile” water) is anticipated (to prevent clinical burns during the procedure) immediately prior to its introduction into the sterile field.*
Due to the concerns for an increased risk for infections, only perform IUSS to process surgical instruments as an exception and in a defined “emergency situation.” Do not use IUSS for implantable devices; however, if an exceptional documented emergency (i.e., as a last resort with no other option available) is encountered and IUSS is deemed absolutely necessary by authorized staffers to process an implant, then in addition to satisfying other criteria, document the specific rare clinical circumstance(s) justifying the use of IUSS to process the implant along with the surgeon’s name (and signature) or the name of another authorized staffer approving its use for this application.
Additionally, this article advises — possibly for the first time — that the use of IUSS to process a surgical instrument, particularly and especially an implantable device, be recorded in the patient’s chart, disclosed (e.g.,via post-operative informed consent), and documented as part of the patient’s permanent medical record to promote transparency and accountability in healthcare, advance a culture of safety, and eliminate preventable harms including surgical site infections.
Some of Dr. Muscarella’s related articles:
- Dr. Muscarella’s Review of the New Multisociety Guidance for Disinfection and Sterilization in Healthcare Facilities. (2025)
- A Proposal to Include Endoscope-Associated Infections as a Reportable Medicare Measure to Promote Patient Safety (2025)
- In Support of Patient Safety, Healthcare Access, and Medicare Payment for a Single-Use Bronchoscope Model (2024)
- Esophageal Tissue Tears and Other Adverse Events Reported When Using Duodenoscopes with a Single-Use Endcap (2023)
Recommendations, summary
In response to his review of the 2025 guidance document, Dr. Muscarella provides the following recommendations to healthcare facilities and surgeons to reduce the risk of confusion associated with IUSS, errors and surgical site infections.
With a focus on medical facilities and patients, this article — the second in a series of two — may provide the most comprehensive review and guidance published to date on the use of IUSS.
The first article in this series — titled “Dr. Muscarella’s Review of the New Multisociety Guidance for Disinfection and Sterilization in Healthcare Facilities” — focuses on other infection prevention topics (not IUSS) discussed in the multisociety document and may be read by clicking here.
1. IUSS may be performed for surgical instruments, but only as an exception and in a defined “emergency situation.”
A. Ensure that the facility’s policy and procedures (P&Ps) restrict the use of IUSS for processing a surgical instrument to only emergency situations.
Notes:
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- A study published last year reported IUSS to be associated with a significantly increased risk for SSIs for transplant and plastic surgeries.
- Another study published this September documented an association between a reduction in the use of IUSS during hip and knee surgeries and a statistically significant decrease in SSIs.
B. Confirm that these P&Ps either define an “emergency situation” or, alternatively, provide an inclusive list of virtually all of the specific clinical emergency scenarios that might justify or permit the use of IUSS to process an instrument.
a. Examples of such clinical circumstances may include the re-sterilization of a non-replaceable, unwrapped instrument that accidentally dropped on the operating room floor during the surgical procedure.
Note: Some facilities may define “an emergency” in the context of IUSS more broadly as “a clinical situation in which any delay incurred places the patient at risk of imminent harm to life, or serious threat to health.”
B. If an “emergency situation” is encountered (as defined in the facility’s P&Ps) for which IUSS may be justified:
a. Review the surgical instrument’s instructions for use (IFUs) to ensure its labeling does not explicitly contraindicate the use of IUSS in any circumstance.
b. Document in the appropriate forms (i.e., the IUSS log and/or the early release form) the details of the specific clinical circumstance and reason(s) justifying IUSS’s use, consistent with the facility’s P&Ps.
i. Additionally, record on the appropriate forms:
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- the IUSS cycle’s time, temperature and pressure
- the load’s contents
- the results of the biological indicator (BI) contained within a process challenge device (PCD)
- the patient’s name (or the patient’s unique identifier); and
- all other relevant cycle and case information (e.g., the surgeon’s name).
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Notes:
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- Such documentation is important for epidemiological tracking (e.g., in the case of a surgical site infection, or a positive BI result).
- This article advises that the use of IUSS to process the surgical instrument be recorded in the patient’s chart, disclosed (e.g., via post-operative informed consent), and documented as part of the patient’s permanent medical record to promote transparency and accountability in healthcare, advance a culture of safety, and eliminate preventable harms including SSIs.
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This article is likely the first to instruct that the use of IUSS to process an instrument, but particularly and especially an implantable device, be disclosed and recorded as part of the patient’s permanent medical record to promote transparency in healthcare, improve safety and eliminate preventable harms. — Lawrence F. Muscarella, Ph.D.
2. Do not use IUSS for implantable devices.
A. Ensure that the facility’s P&Ps advise against the use of IUSS for processing an implantable device due to the potential for legal exposure and “serious infections” (the advice of some other guidance documents notwithstanding).
Notes:
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- While this article, like the VHA’s directive, opposes use of IUSS for processing implants, it recognizes that the 2025 multisociety guidance and the P&Ps of some U.S. medical facilities permit its practice (under certain circumstances).
- A study published last year reported IUSS to be associated with a significantly increased risk for SSIs for transplant and plastic surgeries.
- Another study published this September documented an association between a reduction in the use of IUSS during hip and knee surgeries and a statistically significant decrease in SSIs.
B. However, if an exceptional documented emergency (i.e., as a last resort with no other option available) is encountered and IUSS is deemed absolutely necessary by authorized staffers to process an implant (per the findings of the facility’s documented risk assessment), then — in addition to the other IUSS cycle data and patient information detailed above:
a. Ensure that, consistent with the facility’s P&Ps, the specific rare clinical circumstance(s) justifying the use of IUSS to process the implant (i.e., the specific, unavoidable “emergency” situation that required using IUSS), along with the surgeon’s name (and signature) approving use of IUSS to process the implant, be described and documented on the appropriate forms (i.e., the IUSS log and/or the early release form).
Notes:
1. This article urges that use of IUSS to process an implantable device be recorded in the patient’s chart, disclosed (e.g.,via post-operative informed consent), and documented as part of the patient’s permanent medical record (e.g., patient disclosure via post-operative informed consent) due to, among other rationale:
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- an “increased risk of inadvertent contamination” of the flashed implant with exogenous microorganisms during the device’s transfer into the sterile field
- the “risks related to wet instruments“
- the “potential for burns” from a hot, flashed instrument
- today’s efforts in government to promote transparency and accountability in healthcare, advance a culture of safety, and eliminate preventable harms
- the risk for serious infections (as underscored by the CDC)
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3. CMS requires proper documentation, writing: “If IUSS must be used for an implantable device, the name of the patient/patient’s unique identifier and any other information needed to accurately link the instrument processed using IUSS back to the patient must be recorded.”
4. CMS clarifies further that “the facility must ensure that any implant subjected to IUSS is accurately traceable to the recipient patient.”
b. Use a BI (along with a Class 5 chemical indicator) to monitor every IUSS cycle when the load contains an implant.
i. Confirm that the results of the BI have been recorded.
ii. Whenever possible, quarantine the implant (e.g., on the back table) releasing it only after the BI (e.g., a rapid-acting BI) yields a negative result.
Note: As the CDC wrote in a 2003 guideline, “Because all implantable devices should be quarantined after sterilization until the results of biological monitoring are known, unwrapped or flash sterilization of implantable items is not recommended.”
Accepting new clients: Dr. Muscarella is accepting new clients requesting expert guidance in infection prevention, hospital infections, sterilization, disinfection, endoscope reprocessing and related topics — click here for more details.
Article by: Lawrence F Muscarella, PhD. LFM Healthcare Solutions, LLC. Dr. Muscarella is the president and founder of LFM Healthcare Solutions, LLC, an independent quality improvement company. Click here for a list of his quality improvement healthcare services. E: Larry@LFM-HCS.com. [LFM-ver-1.0]
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Acknowledgment: This article was sponsored, in its entirety, by LFM Healthcare Solutions, LLC, which is responsible for this article’s content. Dr. Muscarella founded this infection prevention and medical device safety company in 2013.
Expert guidance services: Details about the quality and expert services Dr. Muscarella provides healthcare facilities, patients, device manufacturers and legal representatives are available here.
* Additional disclosures: This article features Dr. Muscarella’s opinions, perspectives and recommendations based on his review and interpretation of the multisociety guidance document (2025). His views are necessarily subject to debate, disagreement and further discussion. Indeed, some of his conclusions and insights about IUSS herein may be incomplete or even potentially incorrect (thus warranting independent review for accuracy). While unrelated to this article, Dr. Muscarella has provided guidance on occasion for Ambu, a manufacturer of single-use flexible endoscopes.