Efficacy of cleaning of unbrushable endoscope channels in automated endoscope reprocessors: evidence of non-compliance in real-world practice

BACKGROUND: The air/water, auxiliary water, and elevator wire channels of endoscopes are narrow (0.06-0.14 cm), long (129-345 cm), and cannot be brushed manually. These 'unbrushable' channels depend solely on flushing during reprocessing, and are prone to residual debris and biofilm accumulation. This study evaluated the efficacy of cleaning of these channels in automated endoscope reprocessors (AERs), and assessed compliance with detergent instructions for use (IFUs). METHODS: Endoscopes were reprocessed in an AER using a standardized protocol with high-level disinfection at 20 °C using peracetic acid. The efficacy of cleaning was verified using the FlexiCheck system with stainless steel test coupons coated with standardized blood and polysaccharide soils. Three detergents - one non-enzymatic (Product A) and two enzymatic (Products B and C; IFU: 25-60 °C) - were tested at 1:200 dilution for 1, 5 and 10 min under summer and winter conditions. A nationwide survey of 19 endoscopy centres assessed real-world AER cleaning practices and IFU compliance. RESULTS: In winter, low water temperatures impaired enzymatic activity, reducing the efficacy of cleaning. Product A achieved effective cleaning at ≥5 min across all temperatures. Product B showed temperature- and time-dependent efficacy, while Product C failed under all tested conditions. Survey data revealed substantial variability in detergent use, cleaning duration, and temperature control, with frequent non-compliance with IFUs. Only two centres (10.5%) performed in-AER cleaning verification. CONCLUSIONS: Effective reprocessing of unbrushable channels requires detergent compatibility with AER settings, temperature monitoring, adequate cleaning time, and routine verification of the efficacy of cleaning.