Covering the biopsy hole check valve with “enzymolysis gauze” reduces bacterial contamination in the endoscopy room

doi:10.3748/wjg.v31.i44.113650

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World Journal of Gastroenterology

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1007-9327

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Baishideng Publishing Group Inc, 7041 Koll Center Parkway, Suite 160, Pleasanton, CA 94566, USA

Randomized Controlled Trial

World J Gastroenterol. Nov 28, 2025; 31(44): 113650
Published online Nov 28, 2025. doi: 10.3748/wjg.v31.i44.113650

Covering the biopsy hole check valve with “enzymolysis gauze” reduces bacterial contamination in the endoscopy room

Hu-Bin Xia, Ying-Dong Hou, Yuan Zhang, Ai-Yu Yu, Qi Ding, Wen-Li Ruan, Yi-Shen Mao, Shu-Jiong Feng, Cong Ding, Yi-Feng Zhou

Hu-Bin Xia, The Fourth School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou First People’s Hospital, Hangzhou 310000, Zhejiang Province, China

Hu-Bin Xia, Ying-Dong Hou, Ai-Yu Yu, Qi Ding, Wen-Li Ruan, Yi-Shen Mao, Shu-Jiong Feng, Cong Ding, Yi-Feng Zhou, Department of Gastroenterology, Affiliated Hangzhou First People’s Hospital, School of Medicine, Westlake University, Hangzhou 310000, Zhejiang Province, China

Hu-Bin Xia, Ying-Dong Hou, Ai-Yu Yu, Qi Ding, Yi-Shen Mao, Shu-Jiong Feng, Cong Ding, Yi-Feng Zhou, Department of Gastroenterology, Key Laboratory of Integrated Traditional Chinese and Western Medicine for Biliary and Pancreatic Diseases of Zhejiang Province, Hangzhou 310000, Zhejiang Province, China

Hu-Bin Xia, Ying-Dong Hou, Ai-Yu Yu, Qi Ding, Yi-Shen Mao, Shu-Jiong Feng, Cong Ding, Yi-Feng Zhou, Department of Gastroenterology, Hangzhou Institute of Digestive Diseases, Hangzhou 310000, Zhejiang Province, China

Hu-Bin Xia, Ying-Dong Hou, Ai-Yu Yu, Qi Ding, Yi-Shen Mao, Shu-Jiong Feng, Cong Ding, Yi-Feng Zhou, Department of Gastroenterology, Key Laboratory of Clinical Cancer Pharmacology and Toxicology Research of Zhejiang Province, Hangzhou 310000, Zhejiang Province, China

Yuan Zhang, Department of Gastroenterology, The Second People’s Hospital of Fuyang District, Hangzhou 310000, Zhejiang Province, China

Author contributions: Xia HB wrote the manuscript; Zhou YF funded this article; Hou YD collected bacteria; Zhang Y, Yu AY, and Ding Q prepared all the figures; Ruan WL, Mao YS, Feng SJ, and Ding C are involved in bacterial counting. All the authors have read and revised this article.

Supported by the Construction Fund of Key Medical Disciplines of Hangzhou, No. 2025HZGF05; the Key R and D Program of Zhejiang Province, No. 2023C03054 and No. 2024C03048; the Key Discipline of Integrated Chinese and Western Medicine (Digestive Diseases) in Zhejiang Province, No. 2024-XK-61; and the Zhejiang Province Medical and Health Science and Technology Plan Project, No. 2021KY848.

Institutional review board statement: This study was conducted at the Endoscopy Center and received ethical approval from Hangzhou First People’s Hospital (Approval No. 2025ZN007-1).

Clinical trial registration statement: Prospective registration of this study was completed in the Chinese Clinical Trials Registry (No. ChiCTR2500097549, https://www.chictr.org.cn/) on February 20, 2025.

Informed consent statement: All patients provided written informed consent before participation.

Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.

CONSORT 2010 statement: The authors have read the CONSORT 2010 Statement, and the manuscript was prepared and revised according to the CONSORT 2010 Statement.

Data sharing statement: Consent was not obtained, but the presented data are anonymized and the risk of identification is low.

Open Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/

Corresponding author: Yi-Feng Zhou, MD, Chief, Department of Gastroenterology, Affiliated Hangzhou First People’s Hospital, School of Medicine, Westlake University, No. 261 Huansha Road, Shangcheng District, Hangzhou 310000, Zhejiang Province, China. zhouyifeng@hospital.westlake.edu.cn

Received: September 1, 2025
Revised: October 10, 2025
Accepted: October 27, 2025
Published online: November 28, 2025
Processing time: 89 Days and 16.1 Hours

Abstract

BACKGROUND

Bacterial contamination during colonoscopy is a significant concern, yet few studies have evaluated bacterial aerosols. This study aimed to determine whether covering the biopsy hole check valve with enzymolysis gauze (refers to sterile gauze soaked in a multi-enzyme cleaning solution) reduces bacterial air pollution in endoscopy rooms.

AIM

To evaluate the efficacy of an enzymolysis gauze cover in reducing bacterial aerosols from the biopsy valve.

METHODS

This prospective, single-blind trial included 80 patients undergoing elective diagnostic colonoscopy. During the procedure, the biopsy hole check valve was either covered or left uncovered with enzymolysis gauze. Air samples (100 L) were collected at a distance of 30 cm from the biopsy hole check valve and approximately 140 cm above the floor using a percussive air sampling instrument. Gram-positive bacteria were cultured on standard 90 mm colimycin nalidixic agar blood plates. The primary outcome measures were bacterial load and species identification.

RESULTS

Covering the biopsy hole check valve with enzymolysis gauze reduced bacterial load near the check valve from 50 colony-forming unit (CFU)/m³ [interquartile range (IQR): 30-80] to 20 CFU/m³ (IQR: 10-20). At the end of the procedure each day, covering the valve also decreased bacterial load in the endoscopy room from 35 CFU/m³ (IQR: 33-85) to 10 CFU/m³ (IQR: 5-10). The predominant bacteria identified were Gram-positive cocci.

CONCLUSION

Applying enzymolysis gauze to cover the biopsy hole check valve significantly reduces bacterial aerosol contamination in endoscopy rooms during colonoscopy.

Keywords: Bacterial contamination; Aerosol; Enteric bacterial microflora; Colonoscope; Endoscopy; Enzymolysis gauze; Biopsy hole check valve; Infection

Core Tip: Endoscopy-related infections are underestimated due to difficulties in diagnosis, misdiagnosis, and underreporting. Bacterial contamination during colonoscopy poses a significant challenge, yet limited research has focused on bacterial aerosols, particularly those originating from the biopsy valve. This study introduces a simple yet effective approach to mitigate bacterial aerosol contamination in the endoscopy room. Our findings demonstrate that covering the biopsy valve with an enzymolysis gauze during colonoscopy significantly reduces airborne bacterial aerosols. This could improve safety for both patients and healthcare personnel.