Endoscopes May Not Be as Clean as You Think


Investigators found that scratches, chips, and dents on reusable medical scopes frequently occur and are havens for blood, tissue, and bacteria. A new study suggests that damaged scopes are not amenable to proper cleaning methods, and some damage may be difficult to identify without enhanced inspection. Evidence of contamination via bacterial growth in culture may be delayed beyond 48 hours.


Researchers inspected 20 colonoscopes and esophago­gastro­duodeno­scopes over a seven-month period. All scopes were relatively new (<= 2½ years old) with fewer than 530 uses. Each endoscope was repeatedly examined and cultured over a seven month period of further use. Observations showed that many of the scopes studied had or developed discoloration, scaly deposits, fluid, debris, scratches, and dents on the external surfaces. Using aggressive culturing techniques, bacterial growth was found 60 percent of the time. In one-third of the positive cultures, the culture was negative at 48 hours only to become positive within seven days.

The authors concluded that: “more rigorous reprocessing practices may not be sufficient to ensure that patient-ready endoscopes are free from residual contamination, particularly when the endoscope has defects that could harbor organic debris and biofilm. Visual inspection and routine monitoring for biochemical markers of residual contamination may be essential to identify suboptimal reprocessing and proactively identify endoscopes in need of repair or refurbishment.”

The ANSI/AAMI standard for flexible and semi-rigid endoscope processing (ST91:2015) includes in its quality assurance recommendations that health care facilities “Incorporate visual inspections and testing of the equipment to identify conditions that may affect the cleaning or disinfecting processes, such as testing for leaks, examination for cracks, and checking the integrity of fiber optic bundles.” This study underlines the importance of carefully examining endoscopes for damage that could compromise the efficacy of sterility procedures.



Ofstead CL et al. Longitudinal assessment of reprocessing effectiveness for colonoscopies and gastroscopes: Results of visual inspections, biochemical markers, and microbial cultures. (2017). Am J Infect Control. 45(2): e26-e33. Available online:

Terhune, Chad. “Bacteria Survive Cleaning Efforts in Damaged Medical Scopes, Study Finds,” Los Angeles Times (Los Angeles, CA), January 31, 2017. Available online:

ANSI/AAMI ST91:2015: Flexible and semi-rigid endoscope processing in health care facilities. (2015). AAMI