Prospective Study Assessing Impact of Ethylene Oxide Sterilization on Endoscopic Ultrasound Image Quality.

BACKGROUND AND AIMS: Duodenoscope-associated transmission of infections has raised questions about efficacy of endoscope reprocessing using high-level disinfection (HLD). Although ethylene oxide (ETO) gas sterilization is effective in eradicating microbes, the impact of ETO on endoscopic ultrasound (EUS) imaging equipment remains unknown. In this study we aimed to compare the changes in EUS image quality associated with HLD versus HLD followed by ETO sterilization.

METHODS: Four new EUS instruments were assigned to 2 groups: Group 1 (HLD) and Group 2 (HLD+ETO). The echoendoscopes were assessed at baseline, monthly for 6 months and once every 3-4 months thereafter, for a total of 12 time points. At each time point review of EUS video and still image quality was performed by an expert panel of reviewers along with phantom-based objective testing. Linear mixed effects models were used to assess whether the modality of reprocessing impacted image and video quality.

RESULTS: For clinical testing, mixed linear models showed minimal quantitative differences in linear analog score (p=0.04; estimated change 3.12, scale 0-100) and overall image quality value (p=0.007; estimated change -0.12, scale 1-5) favoring ETO but not for rank value (p=0.06). On phantom testing, maximum depth of penetration was lower for ETO endoscopes (p<0.001; change in depth 0.49 cm).

CONCLUSION: In this prospective study, expert review and phantom-based testing demonstrated minimal differences in image quality between echoendoscopes reprocessed using HLD versus ETO+HLD over 2 years of clinical use. Further studies are warranted to assess the long-term clinical impact of these findings. In the interim, these results support use of ETO sterilization of EUS instruments if deemed clinically necessary.