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Nationwide systematic survey of duodenoscopes

  • A study from the Netherlands investigated the prevalence of contamination among duodenoscopes used for endoscopic retrograde cholangiopancreatography (ERCP) [1].

  • Cases of contamination occurred with all types of duodenoscopes from various manufacturers.

  • In most cases, microorganisms of gastrointestinal and oral origin were found.

Endoscopic retrograde cholangiopancreatography (ERCP) is an important and common procedure. Despite rule-compliant reprocessing, outbreaks with multidrug-resistant pathogens occur in some cases due to contaminated duodenoscopes. A team of experts in the Netherlands has therefore initiated a study on the prevalence of contaminated duodenoscopes [1]. In contrast to procedures with gastroscopes and colonoscopes, ERCPs are more invasive and are commonly performed on immunocompromised patients.

Sixty-seven ERCP centers in the Netherlands participated in this cross-sectional study. It was found that numerous duodenoscopes were contaminated with pathogens of gastrointestinal and oral origin, as well with microorganisms of the skin and the water flora.

701 samples from 150 duodenoscopes analyzed

Centrally supplied sampling kits were used to collect a total of 745 samples from 155 duodenoscopes at the 67 participating centers. Based on various exclusion criteria, 701 samples from 150 duodenoscopes were ultimately included in the analysis. Samples were taken from ten distinct duodenoscope types manufactured by Olympus, Pentax, and Fujifilm. Depending on the duodenoscope type, four to six sites were sampled and cultured centrally.

In the Netherlands, regular microbiological hygiene checks on endoscope channels are not required and are therefore not routinely performed. For this study, sampling was performed by the endoscopy staff based on the instructions/video provided. All samples returned were processed in the same laboratory.

In this study contamination was defined as:

  1. Microbial growth of ≥ 20 colony-forming units (CFUs)/20 ml (any microorganism, abbreviated to AM20)

  2. A Presence of microorganisms with gastrointestinal or oral origin, regardless of the CFU count (abbreviated to MGO).

Contamination regardless of duodenoscope type

Based on the two definitions, a high proportion of contaminated scopes was detected among the duodenoscopes from all manufacturers. Thus, 33 (22%) of duodenoscopes from 26 (39%) of the ERCP centers were contaminated. Pathogens of gastrointestinal and oral origin were detectable on 23 (15%) of the duodenoscopes, including Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, and yeasts, as well as Moraxella spp. and Streptococcus salivarius. Contamination was found on duodenoscopes of all types, regardless of any specific design.

Contamination of ready-to-use duodenoscopes based on the two definitions of contamination (AM20 and MGO)

Chart edited by OLYMPUS based on data of Rauwers AW et al. High prevalence rate of digestive tract bacteria in duodenoscopes: a nationwide study, Gut. 2018;67:1637–1645 [1].

*AM20: Microbial growth of ≥ 20 CFU/20 mL with any species of microorganism 
**MGO: Presence of any microbial growth from microorganisms of gastrointestinal or oral origin

Duodenoscope typeNumberAM20* ContaminatedAM20* Not contaminatedMGO** ContaminatedMGO** Not contaminated
All duodenoscopes15033 (22%)117 (78%)23 (15%)127 (85%)
Olympus TJF-Q180V6915 (22%)54 (78%)15 (22%)54 (78%)
Olympus TJF-160VR4313 (30%)30 (70%)6 (14%)37 (86%)
Olympus TJF-160R81 (13%)2 (87%)08
Olympus TJF-140R20202
Olympus TJF-14520202
Pentax ED34-i10T113 (27%)8 (73%)011
Pentax ED-3490TK80808
Pentax ED-3680TK1011 (100%)0
Fujifilm ED-530XT850505
Fujifilm ED-530XT11 (100%)01 (100%)0

Contamination of ready-to-use duodenoscopes by sampling site

Depending on the duodenoscope type, contamination rates were determined from four to six of the following sampling sites: the biopsy channel, the suction channel, forceps elevator, the distal end, elevator wire channel, and the air and water channel. The forceps elevator and distal end in particular were found to have notably higher contamination values.

Takeaways for practice:

The authors conclude that process controls alone—as they are performed in the Netherlands—are not sufficient. Safety could be increased by introducing a regular sampling and culturing program for endoscopes. A standardized global method would be desirable.

Read the results from the follow-up study here: Dutch study on contamination risks from duodenoscopes and linear ultrasound endoscopes.


  1. Rauwers AW et al. High prevalence rate of digestive tract bacteria in duodenoscopes: a nationwide study, Gut 2018;67:1637–1645. (accessed on 04/23/2021)