Aerosol and droplet generation in upper and lower GI endoscopy: whole procedure and event-based analysis

Post written by Adolfo Parra-Blanco, MD, PhD, from the Department of Gastroenterology, NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and University of Nottingham, and Nottingham Digestive Diseases Centre, and George S.D. Gordon, PhD, from the Optics and Photonics Group, Faculty of Engineering, University of Nottingham, Nottingham, UK.


The aim of this prospective study was to understand the dynamics of aerosol and droplet generation (potential vectors of severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2]) during peroral gastroscopy, transnasal endoscopy, and lower GI endoscopy. 

We examined particle production over whole procedures and immediately after specific events during a procedure: insertion and removal of the endoscope, suction, coughing/gagging/retching, movement of the patient, use of water, insertion and removal of biopsy forceps, and application of anesthetic spray.


Before the coronavirus disease 2019 (COVID-19) pandemic, relatively little was known about the production of aerosols during GI endoscopy. The potential production of aerosols during upper and lower GI endoscopy could have a massive impact on the spreading of SARS-CoV-2. 

Therefore, hospitals needed to understand how to implement adequate protective measures (including personal protective equipment and good ventilation) while minimizing downtime during and after procedures to avoid backlogs.

Our results confirmed the findings by Chan et al1 that peroral gastroscopy is an aerosol-generating procedure (AGP). We found for the first time that transnasal endoscopy and lower GI endoscopy also are AGPs.

Considering the whole procedure, lower GI endoscopy produced more particles than upper GI endoscopy, but peroral gastroscopy generated approximately 40% more particles than lower GI endoscopy per unit of time and nearly twice that of transnasal endoscopy.

Specific events significantly increased the number of particles compared with the background number of particles: throat spray (150.0 times), nasal spray (40.1 times), esophageal extubation (37.5 times), nasal extubation (32.0 times), coughing or gagging (25.8 times), rectal intubation (9.9 times), rectal extubation (27.2 times), application of abdominal pressure (9.6 times), and rectal insufflation or retroflexion (7.7 times). All these events produced particle counts similar or superior to a volitional cough.

In conclusion, upper and lower GI endoscopic procedures are aerosol-generating, and mitigating strategies should be applied, particularly in the context of the COVID-19 pandemic. Further research to evaluate mitigation strategies is required. Some strategies, such as limiting the application of throat and nasal spray, would be applicable now.


  1. Chan SM, Ma TW, Chong MKC, Chan DL, Ng EKW, Chiu PWY. A proof of concept study: esophagogastroduodenoscopy is an aerosol-generating procedure and continuous oral suction during the procedure reduces the amount of aerosol generated. Gastroenterology 2020;159:1949-51.

Parra-Blanco_Gordon_figureRatios of particle counts over entire procedures relative to a reference period before the start of the procedure (normalized to procedure duration). White circles indicate median values, with raw mean counts (not normalized to procedure duration) shown above.

Read the full article online.

The information presented in Endoscopedia reflects the opinions of the authors and does not represent the position of the American Society for Gastrointestinal Endoscopy (ASGE). ASGE expressly disclaims any warranties or guarantees, expressed or implied, and is not liable for damages of any kind in connection with the material, information, or procedures set forth.

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