Efficacy of duodenoscope with disposable distal cap in reducing microbial contamination: A systematic review and meta-analysis

Abstract

BACKGROUND

Persistent microbial contamination of duodenoscopes remains a critical vector for healthcare-associated infections involving multidrug-resistant organisms. Despite adherence to standard high-level disinfection (HLD) protocols, contamination rates remain alarming. To mitigate this risk, the United States Food and Drug Administration has recommended transitioning to duodenoscopes with disposable components.

AIM

To investigate the efficacy of disposable distal cap compared to standard duodenoscope reprocessing with HLD in reducing microbial contamination.

METHODS

Following Preferred Reporting Items for Systematic Reviews and Meta-analysis and Cochrane guidelines, we conducted a systematic search of MEDLINE, EMBASE, Google Scholar, and grey literature for randomized controlled trials comparing disposable distal cap vs standard duodenoscopes. The primary outcome was the rate of microbial contamination, defined as an adenosine triphosphate level > 40 relative light unit. Risk ratio was pooled using a random-effects model, and the quality of evidence was assessed using the Grading Recommendations Assessment, Development, and Evaluation methodology.

RESULTS

Four randomized controlled trials met the inclusion criteria, encompassing 1092 duodenoscopes (543 disposable distal cap, 549 standard). The use of disposable cap demonstrated a significant and substantial reduction in post-HLD contamination rates. The pooled analysis showed a risk ratio of 0.32 (95% confidence interval: 0.16-0.67; P = 0.003), representing a 68% reduction in contamination risk. No statistical heterogeneity was detected (I² = 0%). The overall quality of evidence for this outcome was rated as high.

CONCLUSION

Disposable distal cap significantly decreases microbial contamination rates compared to standard duodenoscope reprocessing protocols. This technology represents a robust and effective strategy to enhance the safety of duodenoscope reprocessing.

Key Words: Duodenoscope with disposable distal cap; Standard duodenoscope; High-level disinfection; Microbial contamination; Systematic review; Meta-analysis

Core Tip: This systematic review and meta-analysis synthesize data from four randomized controlled trials, providing high-quality evidence that disposable distal caps are a highly effective solution to duodenoscope contamination. The primary finding demonstrates a 68% relative risk reduction in microbial contamination, as measured by adenosine triphosphate levels, following high-level disinfection when compared to standard duodenoscopes. This study strongly supports the adoption of disposable distal caps technology as a critical engineering control to enhance reprocessing safety and mitigate the transmission of healthcare-associated infections.

INTRODUCTION

Duodenoscopes are complex medical instruments widely used in diagnosis and therapeutic interventions involving pancreaticobiliary diseases. The intricate design, particularly the presence of an elevator mechanism and narrow channels, makes effective disinfection challenging, often resulting in persistent microbial contamination. This problem has been increasingly recognized as a significant source of healthcare-associated infections, particularly involving multidrug-resistant organisms such as carbapenem-resistant Enterobacteriaceae, posing severe risks to patient safety and leading to increased morbidity and mortality[1,2].

Persistent contamination arises because the complex duodenoscope structure can harbor biofilms, microbial adherents to surfaces, which are particularly resistant to conventional disinfection methods. Despite rigorous adherence to recommended cleaning protocols, including manual cleaning and automated high-level disinfection (HLD), studies have repeatedly shown that microbial residues remain on duodenoscopes, substantially increasing infection risk[3,4].

Given these persistent challenges, regulatory agencies have emphasized enhancing the safety of duodenoscope reprocessing. The United States Food and Drug Administration has issued recommendations encouraging healthcare facilities and manufacturers to transition towards duodenoscopes designed with disposable components. The rationale behind this recommendation is that disposable or single-use components can potentially eliminate the risk associated with inadequate reprocessing, especially in critical components such as the elevator mechanism, which has been particularly implicated in contamination outbreaks[5].

Studies comparing traditional duodenoscope disinfection methods and innovative disposable distal cap approaches have demonstrated varying degrees of efficacy. Recent literature indicates significant reductions in microbial contamination when disposable distal caps are employed, potentially addressing contamination at critical and traditionally difficult-to-clean sites within duodenoscopes[6,7]. Given these considerations, this systematic review and meta-analysis will be the first to evaluate systematically and quantify the efficacy of disposable distal caps in reducing microbial contamination compared to traditional duodenoscope disinfection methods.

MATERIALS AND METHODS

This study was performed by Cochrane Handbook of Systematic Reviews of Interventions[8] and the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines[9] and was registered in the PROSPERO database under the file number CRD420251110449.

Eligibility criteria

Data search was done without limitations of language or publication date. The eligibility criteria adopted were patients undergoing procedures with duodenoscopes and the duodenoscopes themselves, focusing on microbial contamination outcomes. Disposable distal cap HLD protocols for reprocessing duodenoscopes in comparison with standard HLD protocols without the use of disposable cap techniques. Since, an adenosine triphosphate testing (ATP) reading of less than 40 relative light units (RLUs) reliably confirmed the absence of bacterial contamination after reprocessing, showing 100% sensitivity and 100% negative predictive value[10], the outcome of microbial residual contamination after HLD was considered when ATP ≥ 40 RLU. Studies not involving this outcome, and that were not randomized controlled trials (RCTs) were excluded.

Search and study selection

We performed a search in electronic databases (MEDLINE, EMBASE, Google Scholar) and grey literature from their inception until October 2025. As a search strategy, we used descriptors available from the United States National Library of Medicine Medical Subject Headings and other related terms that increased the sensitivity of the search. The following terms were used: (endoscopes OR duodenoscope OR duodenoscopes OR disposable Distal Cap Duodenoscopes OR detachable Elevator Duodenoscopes) AND (disinfection OR reprocessing OR contamination) AND (randomized controlled trial OR RCT OR randomized trial OR randomized clinical trial OR prospective studies).

Data collection process, risk of bias and evidence of quality

The data relating to the studies included and analyzed outcomes were tabulated in Excel tables and individually checked and confirmed by the authors responsible for collecting data. All data extraction was performed independently by two reviewers (Nunes BCM and Duda JR). The revised Cochrane risk-of-bias tool for randomized trials (Rob 2) was used to evaluate the risk of bias[11,12]. The quality of evidence, expressed in high, moderate, low, and very low was assessed utilizing the objective criteria from Grading Recommendations Assessment, Development, and Evaluation using the GRADEpro - Guideline Development Tool software[13].

Statistical analysis

Our outcomes consisted of categorical and continuous variables, whose means and standard deviation values were used for statistical analysis. Mathematical formulas were used for the data conversion in studies that expressed the results in median and interquartile ranges by the McGrath method[14]. The data of interest extracted from the selected studies were meta-analyzed using the RevMan software (Review Manager Software version 5.4-Cochrane Collaboration Copyright^© 2020). The mean values of each continuous outcome were calculated with the 95% confidence interval. P < 0.05 were considered statistically significant, and forest plots exposed the results. Heterogeneity was calculated using the Higgins method[15]. Only the random-effect model was used.

RESULTS

A total of 268 studies were initially identified through database searches. After removing duplicates and applying the eligibility criteria, four studies[6,7,16,17] met the inclusion criteria and were ultimately included in the final analysis, as shown in Figure 1 and Table 1. Part of the included studies[6,16,17] were conducted within the same institution but involved distinct study populations, with no overlap of enrolled patients or duodenoscopes across trials.

Figure 1  Preferred Reporting Items for Systematic Reviews and Meta-analysis flow diagram.

Table 1 Characteristics of the included studies.

Ref.	Comparison	Disposable cap (n)	Standard (n)
Ridtitid et al[16], 2020	Disposable distal cap vs standard duodenoscope	54	54
Ridtitid et al[6], 2022	Disposable distal cap vs standard duodenoscope	200	200
Forbes et al[7], 2023	Disposable distal cap vs standard duodenoscope	208	214
Ridtitid et al[17], 2025	Disposable distal cap vs standard duodenoscope	81	81

Risk of bias

The risk of bias summary for randomized studies using the RoB 2 resulted in an overall low risk in all four studies[6,7,16,17], as shown in Table 2.

Table 2 Revised Cochrane risk-of-bias tool for randomized trials (Rob 2) analysis of included studies.

Ref.	Bias from randomization process	Bias due to deviations from intended interventions	Bias due to missing outcome data	Bias in measurement of the outcomes	Bias in selection of the reported result	Overall risk of bias
Ridtitid et al[16], 2020	Low	Low	Low	Low	Low	Low
Ridtitid et al[6], 2022	Low	Low	Low	Low	Low	Low
Forbes et al[7], 2023	Low	Low	Low	Low	Low	Low
Ridtitid et al[17], 2025	Low	Low	Low	Low	Low	Low

Evidence of quality

The evidence of quality was assessed through the GRADEpro, as seen in Figure 2.

Figure 2 Evidence of quality assessment using the GRADEpro software. GRADE: Grading Recommendations Assessment, Development, and Evaluation; HLD: High-level disinfection; RCT: Randomized controlled trial; ATP: Adenosine triphosphate; RLU: Relative light unit; CI: Confidence interval; RR: Risk ratio.

Microbial residual contamination post-HLD

Disposable distal caps significantly reduced the rate of microbial residual contamination post-HLD by 68% compared to standard duodenoscopes (risk ratio = 0.32; 95% confidence interval: 0.16-0.67; I² = 0%; P = 0.003; Figure 3), with a high level of evidence assessed using GRADEpro (Figure 2).

Figure 3 Forest plot of microbial residual contamination post-high-level disinfection. CI: Confidence interval.

DISCUSSION

The results of this meta-analysis demonstrate that the utilization of disposable distal caps in duodenoscope reprocessing significantly reduces microbial contamination rates compared to traditional HLD practices. This substantial reduction aligns closely with existing literature emphasizing the persistent challenges of effective duodenoscope disinfection due to their intricate design, specifically the presence of narrow channels and elevator mechanisms, which harbor biofilm-forming microorganisms resistant to standard cleaning protocols[1,2,4].

Microbial contamination of duodenoscopes remains a major concern despite strict adherence to reprocessing protocols. Traditionally, microbial culture has been used as the reference method to assess contamination. However, culture-based testing is time-consuming and may underestimate contamination due to residual disinfectants or the presence of non-culturable organisms. ATP bioluminescence testing has emerged as a rapid and sensitive alternative for monitoring reprocessing effectiveness, providing immediate quantitative feedback on residual biological material, demonstrating the reliability of ATP measurement as a quality indicator for endoscope reprocessing[18]. In this meta-analysis, since an ATP level < 40 RLU after reprocessing perfectly ruled out bacterial contamination with 100% sensitivity and 100% negative predictive value[6], ATP measurement was adopted as a sensitive and reproducible method to quantify residual contamination on duodenoscope distal caps in the comparative analysis of reprocessing outcomes.

Historically, duodenoscope contamination has been recognized as a significant contributor to healthcare-associated infections, including outbreaks involving multidrug-resistant organisms. Such infections pose severe threats to patient safety and significantly burden healthcare systems due to prolonged hospitalizations, increased morbidity, and mortality[19-21]. Consequently, interventions aimed at reducing contamination, such as disposable caps, hold critical implications for clinical practice, patient safety, and infection control.

The United States Food and Drug Administration has actively promoted the adoption of duodenoscopes incorporating disposable components, emphasizing that innovative designs substantially decrease infection risk compared to traditional fixed-endoscope designs[5]. The integration of disposable distal caps specifically addresses contamination in the most challenging regions of the endoscope, potentially eliminating residual biofilms that persist despite adherence to standard HLD procedures[6].

Nonetheless, despite the compelling evidence supporting their efficacy, the routine adoption of disposable distal caps remains controversial and limited by significant barriers. Economic factors present a major challenge, as disposable components substantially increase procedural costs. The direct cost implications, combined with indirect factors such as disposal logistics and environmental considerations, pose substantial hurdles, especially for resource-limited settings or institutions with high endoscopy volumes[3,4,22].

Furthermore, the environmental impact associated with increased medical waste generation warrants consideration. Disposable components significantly raise the environmental footprint of endoscopic procedures, an increasingly critical issue given global sustainability concern. Studies exploring environmentally sustainable alternatives, recycling strategies, or innovations in biodegradable materials could be essential in addressing this limitation[7,23].

Additionally, logistic and operational feasibility represents another critical consideration. Incorporating disposable distal caps into routine practice necessitates significant procedural modifications, comprehensive staff training, and adjustments in workflow to manage additional inventory and disposal requirements. These changes, while seemingly minor individually, can cumulatively impact clinical efficiency, potentially causing disruptions in high-volume settings[24,25].

Notably, despite these challenges, the consistency of outcomes across included studies, indicated by the absence of significant heterogeneity (I² = 0%), reinforces the robustness and reliability of the evidence. Yet, caution should be applied in interpreting these results, as the small number of included RCTs (four studies) and the limited total sample size (1092 duodenoscopes) constrain the generalizability of the findings. Hence, further large-scale, multicenter RCTs are essential to corroborate and extend the existing evidence base, thus enhancing the validity and generalizability of these preliminary findings[20,26,27].

Moreover, it is crucial to integrate data regarding clinical outcomes, such as infection rates and patient safety outcomes, beyond microbial contamination metrics. Future research should assess the direct correlation between microbial contamination reductions achieved with disposable distal caps and actual decreases in clinical infection rates. Such data would substantively strengthen the argument for broader adoption of disposable technologies in duodenoscopy, particularly in high-risk patient populations[28,29].

CONCLUSION

Disposable distal cap significantly reduces microbial contamination rates by 68% compared to standard duodenoscope. Despite the robust efficacy demonstrated, indicated by the absence of heterogeneity, widespread adoption faces significant barriers, including increased procedural costs, environmental concerns from medical waste, and logistical challenges. These results underscore the technology’s value, making it imperative for future research to prioritize correlating these contamination reductions with definitive clinical outcomes, such as infection rates, to fully establish the cost-effectiveness of this patient safety intervention.