Colonoscopy Infections: Can the Colonoscope Itself Make You Sick?

Almost everything written about contaminated medical scopes is about duodenoscopes — the specialized instruments used in ERCP procedures on the bile and pancreatic ducts. That focus is earned: duodenoscopes have a complicated tip that is genuinely hard to clean, and they have been tied to the most notorious superbug outbreaks. But patients rarely have ERCPs, and they routinely have colonoscopies. In July 2026, news outlets reported that an Illinois woman had filed suit alleging she developed a serious Clostridioides difficile (“C. diff”) infection after a colonoscopy performed with a reusable Olympus scope. That allegation has not been proven, but it raises a fair question that deserves an honest, evidence-based answer: can a colonoscope itself make you sick?

Colonoscopy Is the Most Common Scope Procedure — and the Scope Is Reused

A colonoscope is a long, flexible tube with a camera, a light, and hollow working channels that carry water, air, and instruments. Like a duodenoscope or a bronchoscope, it is a reusable device: after each patient it is manually cleaned, then run through high-level disinfection (HLD), most often in an automated endoscope reprocessor. Because roughly 15 million colonoscopies are performed in the United States each year, even a small failure rate in that cleaning process is spread across an enormous number of procedures. The organisms of concern are the same ones the FDA flags for duodenoscopes — “high concern” bacteria “more often associated with disease,” including Escherichia coli, Klebsiella, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus. The device is different, but the reprocessing problem is the same one we describe on our colonoscopy infection and hospital reprocessing negligence pages.

Can a Colonoscopy Actually Transmit an Infection?

The honest answer is: yes, it can happen, but serious device-transmitted infection is considered uncommon relative to the number of procedures done. It is important not to overstate the risk — most colonoscopies are safe, and a fever after a procedure has many possible causes. What is well established is that reprocessed colonoscopes are not always as clean as everyone assumes. The FDA has acknowledged for years that reusable flexible endoscopes can remain contaminated even when reprocessing follows the manufacturer’s instructions, and post-market data it required on duodenoscopes found high-concern organisms on more than 5% of properly collected samples — a rate the agency itself called higher than expected. We covered that finding in our piece on the FDA’s 1-in-20 contamination data.

Documented endoscopy-associated transmissions over the years have included antibiotic-resistant bacteria such as carbapenem-resistant Enterobacterales (CRE) and Pseudomonas, and, in reported outbreaks tied to lapses in reprocessing or unsafe injection practices, bloodborne viruses including hepatitis C. The most serious clinical outcome is a post-procedure bloodstream infection that progresses to sepsis. The point is not that colonoscopy is dangerous — it is that when a serious infection does appear in the days after one, “it was just bad luck” is an assumption, not a finding.

Why C. difficile Is the Organism That Worries Reprocessing Experts

C. difficile is different from an ordinary bacterium because it forms spores — a dormant, armored form that is extraordinarily hard to kill. Spores can survive on surfaces for months, tolerate stomach acid, and shrug off disinfectants that wipe out most bacteria. That matters for colonoscopes because standard high-level disinfection is designed to kill vegetative bacteria and viruses; it reduces, but does not reliably eliminate, C. diff spores. Actually destroying spores requires sporicidal chemistry — agents such as glutaraldehyde or peracetic acid used at adequate concentration and exposure time. Under the international reprocessing standard ISO 15883-4, a disinfectant claiming sporicidal performance must achieve at least a 4-log (99.99%) reduction in spores.

The contamination is not hypothetical. A review published in Clinical Microbiology Reviews reported that a study found 10 of 15 colonoscopes contaminated with C. diff immediately after being used on patients with C. diff disease. The reassuring counterpoint, which we include because it is true, is that documented patient-to-patient transmission of C. diff specifically by colonoscopy is rare, and the prevailing view is that thorough cleaning and disinfection after each use makes that risk very low. But “low when done correctly” is precisely the qualifier that a legal investigation exists to test: whether, in a specific case, the cleaning was actually done correctly and whether the right sporicidal process was used.

What the Contamination Studies Found Inside “Clean” Colonoscopes

Some of the most important evidence comes from researchers who tested and looked inside scopes that had already been fully reprocessed. In a multi-year study led by researcher Cori Ofstead and colleagues, microbial growth was found in samples from 47% of fully reprocessed endoscopes at baseline and 60% at follow-up, and borescope examinations — running a tiny camera through the channels — identified scratches, discoloration, debris, and retained fluid inside the devices. Other Ofstead work found retained moisture in roughly half of endoscopes checked, and moisture is exactly what lets surviving organisms multiply between uses. We go deeper into that physical evidence in our article on what borescope inspections reveal about “clean” scopes.

A scratched channel or a pocket of retained fluid gives bacteria — and biofilm — a place to hide, reseed after cleaning, and survive a disinfection cycle. That is the mechanism behind the FDA’s repeated acknowledgment that a device can pass a cleaning protocol and still be contaminated. For a spore-former like C. diff, an incompletely sporicidal process combined with hidden damage is a worst-case pairing.

When a Colonoscopy Infection May Point to a Legal Claim

A scope-infection claim generally runs on two tracks, and a colonoscopy case is no different. One track is hospital reprocessing negligence — whether the facility followed the applicable cleaning, drying, storage, and (for spore-formers) sporicidal steps, and whether it inspected and repaired damaged scopes. The other is product liability against a manufacturer — whether a device was designed or sold in a way that makes reliable cleaning unrealistic. The line between a hospital-negligence claim and a product-liability claim, and how it differs from ordinary medical malpractice, turns on the facts of each case.

Causation is always the hard part. Proving a colonoscopy caused an infection is not about timing alone; it is about matching the organism cultured from the patient to a specific colonoscope through device-tracking logs, reprocessing records, surveillance cultures, and — where isolates are preserved — DNA sequencing. Those records exist, but they are kept on limited retention schedules and can be purged. That is why what a patient does early matters, and it is the subject of our guide to the evidence needed in a scope-infection case.

A Trial Lawyer’s Read

“People assume a colonoscopy is routine, so if they get sick afterward they blame themselves or chalk it up to chance,” says Alex Alvarez, Managing Partner of The Alvarez Law Firm and a Board Certified Civil Trial Lawyer. “I’m not saying every post-colonoscopy infection is a case — most aren’t. What I’m saying is you don’t get to find out by guessing. The first things I want are the device-tracking log showing which scope was used by serial number, the reprocessing and drying records for that scope, and whether any of the patient’s cultures were preserved. If the records show the cleaning was done right, that’s the answer. If they show corners were cut, that’s a different answer — and either way the family deserves to know.”

The medicine has to line up with the microbiology. “A spore-former like C. diff is a good example of why the details matter,” notes Herb Borroto, M.D., J.D., the firm’s Medical-Legal Expert, who holds both a medical degree and a law degree. “Standard high-level disinfection is not designed to reliably kill spores — that takes a sporicidal process. So I look at what agent and cycle the facility actually used, the inspection and repair history of the scope, the culture and typing of the organism, and the timing against the procedure. My job is to say whether the documents support the connection or rule it out. If they fit, they fit. If they don’t, I say so.”

What to Do Now

If you or a loved one developed a serious infection — a bloodstream infection, sepsis, a C. diff infection, or a persistent drug-resistant organism — in the days or weeks after a colonoscopy, endoscopy, ERCP, or bronchoscopy, do not assume it was random simply because there was no outbreak in the news. The evidence that could connect a device to an infection lives in culture results, device-tracking logs, reprocessing records, and inspection histories that are not kept forever. Knowing what to request, and how quickly, can be the difference between a preserved case and a lost one. Our infection symptoms page 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

Can you get an infection from a colonoscopy?

Yes, though serious device-transmitted infections are considered uncommon. The best-documented endoscopy infection risk involves duodenoscopes used in ERCP, but colonoscopes are the same class of reusable flexible endoscope and are cleaned the same way. Peer-reviewed studies led by Cori Ofstead found microbial growth inside 47% of fully reprocessed endoscopes at baseline and 60% at follow-up, and the FDA acknowledges that reusable flexible endoscopes can remain contaminated even when reprocessing follows the manufacturer’s instructions. Most colonoscopies cause no infection, but a serious infection that appears in the days after the procedure is worth investigating rather than dismissing as coincidence.

Why is C. difficile a special concern for colonoscope cleaning?

Clostridioides difficile (C. diff) forms hardy spores that resist the high-level disinfection used to clean most colonoscopes. Spores can survive on surfaces for months and tolerate disinfectants that kill ordinary bacteria; eliminating them requires sporicidal chemistry such as glutaraldehyde or peracetic acid at adequate exposure times. A review in Clinical Microbiology Reviews reported that a study found 10 of 15 colonoscopes contaminated with C. diff immediately after use on patients with C. diff disease. Documented patient-to-patient transmission by colonoscopy is rare, but the combination of resistant spores and confirmed contamination is why sporicidal reprocessing and drying matter.

How would anyone prove a colonoscopy caused an infection?

The proof is built from records and microbiology, not timing alone. Investigators identify the organism cultured from the patient, use the facility’s device-tracking log to determine which specific colonoscope (by serial number) was used, and where possible compare the patient’s organism to organisms recovered from that scope using culturing and whole-genome sequencing. Reprocessing records, borescope inspection and repair histories, and surveillance-culture results fill in whether the device could have been the source. These records are kept only on limited retention schedules, so acting before they are purged matters.

What kinds of infections have been linked to contaminated flexible endoscopes?

Documented endoscopy-associated transmissions include antibiotic-resistant bacteria such as carbapenem-resistant Enterobacterales (CRE) and Pseudomonas aeruginosa, and, in reported outbreaks tied to lapses in reprocessing or injection practices, bloodborne viruses including hepatitis C. Post-procedure bloodstream infection and sepsis are the most serious clinical outcomes. Not every one of these is proven to come from the scope in every case, which is exactly why the device and reprocessing records have to be examined on the specific facts.

Sources

• Ofstead CL, et al. “Persistent contamination on colonoscopes and gastroscopes detected by biologic cultures and rapid indicators despite reprocessing performed in accordance with guidelines.” American Journal of Infection Control (2015) (microbial growth in 47% of reprocessed endoscopes at baseline, 60% at follow-up; borescope-identified scratches, debris, and retained fluid). sciencedirect.com
• Kovaleva J, Peters FTM, van der Mei HC, Degener JE. “Transmission of Infection by Flexible Gastrointestinal Endoscopy and Bronchoscopy.” Clinical Microbiology Reviews (2013);26(2):231–254 (C. diff spore resistance to high-level disinfection; sporicidal agents; report that 10 of 15 colonoscopes were contaminated with C. diff after use on C. diff patients; rarity of documented colonoscopy transmission). pmc.ncbi.nlm.nih.gov
• U.S. Food & Drug Administration — “Infections Associated with Reprocessed Duodenoscopes” and reprocessing communications (definition of “high concern” organisms; recognition that reusable flexible endoscopes can remain contaminated after reprocessing per the manufacturer’s instructions; post-market sampling finding high-concern organisms on more than 5% of properly collected samples). fda.gov
• Centers for Disease Control and Prevention — “Clostridioides difficile Infection” and environmental persistence guidance (spore survival on surfaces; need for sporicidal disinfection). cdc.gov
• iData Research — U.S. annual colonoscopy procedure volume (approximately 15–16.6 million colonoscopies performed in the United States each year). idataresearch.com

This article is for general informational purposes only and is not legal or medical advice. It summarizes published research, public health guidance, and regulatory communications as of the publication date; scientific methods and standards can change, and this article does not describe the outcome of any client’s case. References to a newly filed lawsuit describe allegations that have not been proven. The existence of investigative methods such as culturing and genetic typing is evidence 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.