key: cord-0049390-1fg3ujas
authors: Yen, Andrew W.; Leung, Joseph W.; Shao, Paul P.; Leung, Felix W.
title: Total water exchange colonoscopy to mitigate infection risks due to aerosolization during colonoscopy
date: 2020-08-25
journal: nan
DOI: 10.1002/aid2.13229
sha: 41dff0a9af3af0ead3aa1e31cfc9c987f4f64a6a
doc_id: 49390
cord_uid: 1fg3ujas

nan

Dear Editor, In considering strategies to reduce disease transmission during the COVID-19 pandemic, the topic of aerosolization and dispersion of SARS-CoV-2 during colonoscopy is an area of particular interest. Since colonoscopies constitute the bulk of workload for most endoscopy practices, the postponement of procedures during the pandemic has dramatically cut into revenue streams and delayed services to patients. A recent Danish study 1 suggested plausible harmful impacts for delaying colonoscopy in patients with a positive fecal immunochemical test. Therefore, re-establishing timely access to colonoscopy, when conditions allow, is important and resuming the safe delivery of care will require multiple strategies.

SARS-CoV-2 transmission by aerosol generated at the time of colonoscopy is speculative, but is of concern. Aerosol formation is believed to occur with traditional gas (air or CO 2 ) insufflation when a patient passes flatus; and flatus is known to disseminate bacteria to nearby surroundings. 2 Additionally, modern colonoscopes generate aerosol and microdroplets by their design and function, with leakage at the valves and ports, facilitated by insertion and removal of instruments through the endoscope channel and by pressure gradients created by inflating the colon and suction of gas. The resulting aerosol is suspected to increase the risk of viral transmission to patients and staff through airborne dispersion. Although the risk of aerosolization of viral particles in fecal matter during colonoscopy has not been clearly defined, fecal-oral transmission is possible since SARS-CoV-2 has been detected in colonic biopsy and fecal specimens. 3 Therefore, avoidance of aerosol during colonoscopy may be one worthwhile approach to consider to help mitigate suspected infection risks, but this requires elimination of gas insufflation. How is this possible? We propose total water exchange colonoscopy (TWEC) 4,5 to eliminate gas insufflation. With TWEC, the air button remains off during the procedure and water exchange (WE) 6 is continued for the entire exam. With a transparent cap attached to the tip of the colonoscope, water is infused to distend the lumen, dirty water with residual stool and air pockets are removed with suction until the cecum is reached. 7 Upon cecal intubation, WE is continued during withdrawal. The entire procedure, including polyp removal, 8 is performed without gas, and aerosolization may be minimized. Flatus is not observed with TWEC. Rarely, a very small proportion of patients experience liquid incontinence if the colonoscopist fails to adhere to strict principles of WE, aiming for net equivalence of water infused and water removed at all stages. Despite the lack of quantifiable data regarding reduction in aerosolization, TWEC (avoiding gas insufflation) seems to be a logical, cost-conscious, and easily implemented safeguard to consider in addition to more widely accepted protective measures.

The COVID-19 pandemic has reduced colonoscopy volume globally to abysmally low levels. It is an opportune, if not wanted, time to learn new skills that may play a role in helping to keep patients, staff, and ourselves safe and healthy. Total water exchange colonoscopy may just fit the bill. 

Time to colonoscopy, cancer probability, and precursor lesions in the Danish colorectal cancer screening program

Hot air?

AGA Institute rapid recommendations for gastrointestinal procedures during the COVID-19 pandemic

The feasibility of total water colonoscopy

More than feasibility-total water colonoscopy

A proof-of-principle, prospective, randomized controlled trial (RCT) demonstrating improved outcomes in scheduled unsedated colonoscopy by the water method

A novel method with significant impact on adenoma detection: Combined water-exchange and cap-assisted colonoscopy

Underwater vs. conventional endoscopic resection of non-diminutive non-pedunculated colorectal lesions: a prospective randomized controlled trial (with video)

The authors declare no conflict of interest.Andrew W. Yen 1, 2 Joseph W. Leung 1,2 Paul P. Shao 3,4 Felix W. Leung 3, 4