Why Aren’t Endoscopes Sterilized Between Patients?

It is one of the most common questions patients ask after learning a reused scope may have made them sick: wait — they don’t sterilize it between patients? The honest answer is that, for most reusable flexible endoscopes, they don’t. They disinfect it. Those two words sound interchangeable, but in infection control they mean different things, and the gap between them is not an accident or an oversight — it is written into the rulebook that hospitals have followed for more than fifty years. Understanding that gap is the key to understanding how a scope declared “clean” can still carry a drug-resistant organism into the next person.

The Short Answer: Disinfected, Not Sterilized

Most reusable flexible endoscopes — colonoscopes, gastroscopes, bronchoscopes, and the duodenoscopes used for ERCP — are cleaned between patients by high-level disinfection, not sterilization. High-level disinfection kills bacteria, viruses, fungi, and mycobacteria, but by definition it is not required to eliminate large numbers of bacterial spores. Sterilization — the standard applied to scalpels and surgical implants — destroys all forms of microbial life, spores included. A scope handed back to the endoscopy suite as ready for the next patient was, in almost all cases, disinfected to a high level. It was not sterilized.

The Spaulding Classification: A 1968 Rule That Still Governs Scope Cleaning

Why is a device that goes deep inside the body allowed to be merely disinfected? The answer is a framework created by microbiologist Earle H. Spaulding in 1968 and later adopted as the backbone of the CDC’s Guideline for Disinfection and Sterilization in Healthcare Facilities (Rutala & Weber, published in 2008). Spaulding’s insight was to match the intensity of cleaning to how the device is used, sorting every instrument into three tiers:

• Critical items enter sterile tissue or the vascular system — surgical instruments, implants, biopsy forceps. These must be sterilized.
• Semicritical items contact mucous membranes or non-intact skin but do not, in theory, breach sterile tissue. These require, at minimum, high-level disinfection.
• Noncritical items touch only intact skin — blood-pressure cuffs, stethoscopes. These need only low-level disinfection.

Under this scheme, flexible endoscopes are classified as semicritical, because they travel through the gastrointestinal or respiratory tract — mucosal surfaces, not sterile spaces. That single classification is why the terminal cleaning step for a colonoscope or a duodenoscope is high-level disinfection rather than sterilization. It is not that anyone decided sterilization would be nice but skipped it. The governing standard has never required it for these devices.

High-Level Disinfection vs. Sterilization: What’s Actually Different

The distinction is precise. Sterilization is defined as the complete destruction or elimination of all forms of microbial life, including the tough, dormant bacterial spores that ordinary disinfectants struggle to kill. High-level disinfection is a chemical process that eliminates all microorganisms except large numbers of those spores. For flexible endoscopes, high-level disinfection is usually done with a liquid chemical — glutaraldehyde, ortho-phthalaldehyde (OPA), or peracetic acid — most often inside an automated endoscope reprocessor that pumps the disinfectant through the scope’s internal channels.

On paper, the practical difference can look small: appropriately high-level disinfected endoscopes have rarely been tied to spore-forming infections, and for many procedures high-level disinfection is genuinely adequate. But “adequate on paper” assumes the process worked perfectly — every channel brushed, every surface contacted, the water clean, the drying complete. High-level disinfection leaves a smaller margin for error than sterilization does. When a scope is scratched, has a buried defect, is rushed, or is rinsed with contaminated water, that thin margin is where infections happen.

Why Not Just Sterilize Every Scope? The Heat Problem

If sterilization is safer, the obvious question is why hospitals don’t simply sterilize scopes too. The main obstacle is physical. The fast, cheap, reliable sterilization method most hospitals depend on is the steam autoclave — and flexible endoscopes are heat- and moisture-sensitive precision instruments packed with fiber optics, adhesives, and long polymer channels that high-heat steam can damage or destroy. You cannot autoclave a duodenoscope the way you autoclave a clamp.

Low-temperature sterilization that does not rely on heat does exist. Ethylene oxide (EtO) gas sterilization works on heat-sensitive instruments, and the FDA has stated that EtO may be an effective method for devices such as duodenoscopes. Liquid chemical sterilization is another option. But these processes are slower, less widely available, and more costly than a disinfection cycle, and EtO uses a toxic, flammable gas with lengthy aeration times and its own safety burden — so a single scope can be out of service far longer. Faced with those trade-offs and a rulebook that only required high-level disinfection, most facilities kept disinfecting. The safer method was available; it just wasn’t mandatory, fast, or cheap.

The Duodenoscope Problem: A “Semicritical” Device Doing “Critical” Work

Here is where the tidy 1968 categories start to strain. A duodenoscope is classified as semicritical — a mucous-membrane device. But during an ERCP, it threads a wire, dye, and instruments up into the bile duct and pancreatic duct — spaces that are normally sterile. By the logic of Spaulding’s own framework, contact with sterile territory is the hallmark of a critical device that should be sterilized. In other words, the duodenoscope is often doing critical-tier work while being cleaned to a semicritical-tier standard.

This is not a fringe complaint. In the infection-prevention literature — including a 2023 review in the American Journal of Infection Control on the shift from high-level disinfection to sterilization for endoscopes — expert panels have recommended reclassifying duodenoscopes from semicritical to critical precisely so that sterilization becomes the expected standard. The device’s complex, hard-to-clean design compounds the problem: the elevator mechanism at the tip has tiny moving parts and crevices that trap tissue and bacteria, which is exactly why a merely-disinfected duodenoscope became the vehicle for outbreak after outbreak.

What the FDA Has Actually Said

The regulators did not stay silent as the CRE “superbug” outbreaks mounted. In an August 2015 Safety Communication, “Supplemental Measures to Enhance Duodenoscope Reprocessing,” the FDA laid out four steps facilities could add on top of standard cleaning: (1) microbiological culturing of the scope, (2) a second round of high-level disinfection, (3) liquid chemical sterilization, and (4) ethylene oxide sterilization. In that same communication the agency stated that duodenoscopes “should be sterilized, due to the greater margin of safety provided by sterilization” when possible and practical — while acknowledging that, at minimum, they require high-level disinfection after each use.

The FDA has also acknowledged something blunt: reusable flexible endoscopes can remain contaminated even after reprocessing performed according to the manufacturer’s instructions. Its postmarket sampling of reprocessed duodenoscopes found that a meaningful share still carried “high-concern” organisms after cleaning — the finding behind our piece on the roughly 1-in-20 contamination rate. Then, in an April 2019 Safety Communication, the FDA recommended that hospitals and manufacturers begin transitioning to duodenoscopes with disposable components or fully disposable designs, and it later urged facilities to complete that transition. The regulatory arc is telling: the agency moved from “disinfect,” to “disinfect plus supplemental measures, ideally sterilize,” to “stop reusing the parts you can’t reliably clean at all.”

Why This Matters to a Scope-Infection Case

A scope-infection claim generally runs on two tracks. One is product liability against the manufacturer — whether a device was designed or sold in a way that makes reliable cleaning unrealistic. The other is hospital reprocessing negligence — whether the facility followed the applicable cleaning, water-quality, drying, and monitoring steps. The disinfection-versus-sterilization distinction runs straight through both.

On the product side, a device that routinely enters sterile ducts but cannot be reliably sterilized, and whose own design traps the organisms cleaning is supposed to remove, raises a squarely legal question about whether the risks were reasonable and adequately warned. On the facility side, the FDA had already told hospitals that supplemental measures — culturing, repeat disinfection, sterilization — existed and offered a greater margin of safety. What method a specific hospital used on a specific scope, whether it adopted any of the supplemental measures, and when it moved toward disposable components are not matters of opinion. They live in the reprocessing logs, purchasing records, and device-tracking files — records kept on limited retention schedules, which is why preserving them early matters.

A Trial Lawyer’s Read

“The first time most jurors hear that the scope wasn’t sterilized — just disinfected — they lean forward,” says Alex Alvarez, Managing Partner of The Alvarez Law Firm and a Board Certified Civil Trial Lawyer. “They assumed sterile, like an operating room. My job isn’t to make the hospital the villain for following a fifty-year-old classification — it’s to show what they knew and what they chose. The FDA told these facilities in 2015 that sterilization gave a greater margin of safety and listed the supplemental steps. So I want the records: what did you do to this scope, did you add any of those measures, and when did you start moving to disposable parts? The paper answers the question.”

The medicine has to line up with the paperwork. “High-level disinfection is a real, validated process — done right, it works most of the time,” notes Herb Borroto, M.D., J.D., the firm’s Medical-Legal Expert, who holds both a medical degree and a law degree. “But ‘most of the time’ is doing a lot of work in that sentence. When I review a case, I look at the organism, the timing, and the method used on that device. If a patient grows a resistant organism after an ERCP and the scope was only high-level disinfected — on a device the FDA itself said should be sterilized where practical — that combination is exactly what the standards were trying to prevent. My role is to say honestly whether the records support the connection or rule it out.”

What to Do Now

If you or a loved one developed a serious infection — a bloodstream infection, sepsis, or a drug-resistant organism — in the days or weeks after a colonoscopy, ERCP, cystoscopy, or bronchoscopy, do not assume the device must have been sterile just because it was “cleaned.” It was almost certainly high-level disinfected, and whether that was appropriate, and whether it was done correctly, is a records question. Knowing what to request, and how quickly, can be the difference between a preserved case and a lost one. Our guide to the signs a scope caused an infection can help you recognize the warning signs worth taking seriously.

A short, no-obligation review can tell you whether the facts warrant pulling those records and whether a filing deadline may be approaching. We represent patients nationwide. Free case review. No Fees Unless We Recover Money for You.

Frequently Asked Questions

Are reusable endoscopes sterilized between patients?

Usually not. Most reusable flexible endoscopes — including colonoscopes, gastroscopes, bronchoscopes, and the duodenoscopes used for ERCP — are cleaned with high-level disinfection between patients, not sterilization. Under the Spaulding classification used in the CDC’s disinfection guideline, these scopes are treated as semicritical devices, and semicritical devices require high-level disinfection as their minimum terminal step. High-level disinfection kills bacteria, viruses, fungi, and mycobacteria, but by definition it does not reliably destroy large numbers of bacterial spores, whereas sterilization is defined as the destruction of all microbial life including spores. In practice this means a scope declared clean and returned to service was disinfected, not sterilized.

What is the difference between high-level disinfection and sterilization?

Sterilization is defined as the complete destruction or elimination of all forms of microbial life, including bacterial spores. High-level disinfection is a chemical process that kills all microorganisms except large numbers of bacterial spores. Sterilization is the higher standard and the one required for critical devices that enter sterile tissue; high-level disinfection is the standard set for semicritical devices that contact mucous membranes. For flexible endoscopes, high-level disinfection is typically performed with liquid chemicals such as glutaraldehyde, ortho-phthalaldehyde (OPA), or peracetic acid, often inside an automated endoscope reprocessor. The difference matters because high-level disinfection, even performed perfectly, leaves a smaller margin of safety than sterilization.

Why aren’t duodenoscopes just sterilized if sterilization is safer?

Mainly because duodenoscopes are heat- and moisture-sensitive precision instruments that can be damaged by the high heat of a standard steam autoclave, which is the fast, inexpensive sterilization method most hospitals rely on. Low-temperature sterilization that does not rely on heat does exist — ethylene oxide (EtO) gas sterilization and liquid chemical sterilization — and the FDA has said EtO can be effective for heat-sensitive instruments such as duodenoscopes. But these methods are slower, less widely available, and more expensive, and EtO involves a toxic gas with its own handling and turnaround limits. Because of those practical constraints, most facilities have continued to rely on high-level disinfection as the routine terminal step.

Why does high-level disinfection instead of sterilization matter to a scope-infection lawsuit?

Because it frames what the manufacturer and hospital knew and chose. A scope-infection claim generally runs on product liability against the manufacturer and hospital reprocessing negligence. The FDA has acknowledged that reusable flexible endoscopes can remain contaminated after reprocessing according to the manufacturer’s instructions, and after the CRE superbug outbreaks it recommended supplemental measures including sterilization and, later, a transition to disposable-component and single-use duodenoscopes. Whether a device that threads into normally sterile ducts should have been reliably sterilizable, and whether a facility used the safer available measures, are central questions. The reprocessing records, device-tracking logs, and the method used on a specific scope are the evidence that answers them.

Sources

• Rutala WA, Weber DJ, and the Healthcare Infection Control Practices Advisory Committee (HICPAC) — Centers for Disease Control and Prevention, “Guideline for Disinfection and Sterilization in Healthcare Facilities” (2008; updates) (Spaulding classification of critical, semicritical, and noncritical devices; definitions of sterilization and high-level disinfection; classification of flexible endoscopes as semicritical). cdc.gov
• Spaulding EH — Original classification framework matching required disinfection or sterilization to a device’s intended use (1968), foundation of the CDC guideline.
• U.S. Food & Drug Administration — “Supplemental Measures to Enhance Duodenoscope Reprocessing: FDA Safety Communication” (August 4, 2015) (four supplemental measures — microbiological culturing, repeat high-level disinfection, liquid chemical sterilization, and ethylene oxide sterilization; statement that duodenoscopes should be sterilized where possible for a greater margin of safety; EtO effective for heat-sensitive instruments). fda.gov
• U.S. Food & Drug Administration — “Infections Associated with Reprocessed Duodenoscopes” (reusable flexible endoscopes can remain contaminated after reprocessing per the manufacturer’s instructions; definition of “high concern” organisms; postmarket surveillance sampling results). fda.gov
• U.S. Food & Drug Administration — “FDA recommends health care facilities and manufacturers begin transitioning to duodenoscopes with disposable components to reduce risk of patient infection” (Safety Communication, April 2019; later transition updates). fda.gov
• “Reprocessing semicritical items: an overview and an update on the shift from high-level disinfection to sterilization for endoscopes,” American Journal of Infection Control (2023) (debate over reclassifying duodenoscopes from semicritical to critical; movement toward terminal sterilization). ajicjournal.org

This article is for general informational purposes only and is not legal or medical advice. It summarizes published consensus classifications, reprocessing standards, public health guidance, and regulatory communications as of the publication date; standards and scientific methods can change, and this article does not describe the outcome of any client’s case. References to reprocessing methods, regulatory recommendations, and outbreaks describe published findings, not any individual’s claim. The existence of alternative methods such as sterilization or disposable devices is context to be evaluated on the facts, not proof of any individual’s claim. Nothing here creates an attorney-client relationship, and no result is promised or implied. Past results do not guarantee future outcomes. Deadlines and legal standards vary by state and by the facts of each case. If you believe you may have a claim, consult a licensed attorney promptly.