Measuring Droplets Expelled During Endoscopy to Investigate COVID-19 Transmission Risk

Biopsy channel of the endoscope as a potential source of infectious droplets during GI endoscopy

BACKGROUND AND AIMS

During endoscopy, droplets with the potential to transmit infectious diseases are known to emanate from a patient's mouth and anus, but they may also be expelled from the biopsy channel of the endoscope. The main goal of our study was to quantify droplets emerging from the biopsy channel during clinical endoscopy.

METHODS

A novel light-scattering device was used to measure droplets emanating from the biopsy channel. An endoscopy model was created, and in vitro measurements were carried out during air insufflation, air and water suctioning, and the performance of biopsy sampling. Similar measurements were then made on patients undergoing endoscopy, with all measurements taking place over 2 days to minimize variation.

RESULTS

During in vitro testing, no droplets were observed at the biopsy channel during air insufflation or air and water suctioning. In 3 of 5 cases, droplets were observed during biopsy sampling, mostly when the forceps were being removed from the endoscope. In the 22 patients undergoing routine endoscopy, no droplets were observed during air insufflation and water suctioning. Droplets were detected in 1 of 11 patients during air suctioning. In 9 of 18 patients undergoing biopsy sampling and 5 of 6 patients undergoing snare polypectomies, droplets were observed at the biopsy channel, mostly when instruments were being removed from the endoscope.

CONCLUSIONS

We found that the biopsy channel may be a source of infectious droplets, especially during the removal of instruments from the biopsy channel. When compared with droplets reported from the mouth and anus, these droplets were larger in size and therefore potentially more infectious.

Severe Acute Respiratory Syndrome Coronavirus 2 Is Detected in the Gastrointestinal Tract of Asymptomatic Endoscopy Patients but Is Unlikely to Pose a Significant Risk to Healthcare Personnel

Background and Aims

Recent evidence suggests that the gut is an additional target for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, whether SARS-CoV-2 spreads via gastrointestinal secretions remains unclear. To determine the prevalence of gastrointestinal SARS-CoV-2 infection in asymptomatic subjects, we analyzed gastrointestinal biopsy and liquid samples from endoscopy patients for the presence of SARS-CoV-2.

Methods

We enrolled 100 endoscopic patients without known SARS-CoV-2 infection (cohort A) and 12 patients with a previous COVID-19 diagnosis (cohort B) in a cohort study performed at a regional hospital. Gastrointestinal biopsies and fluids were screened for SARS-CoV-2 by polymerase chain reaction (PCR), immunohistochemistry, and virus isolation assay, and the stability of SARS-CoV-2 in gastrointestinal liquids in vitro was analyzed.

Results

SARS-CoV-2 ribonucleic acid was detected by PCR in the colonic tissue of 1/100 patients in cohort A. In cohort B, 3 colonic liquid samples tested positive for SARS-CoV-2 by PCR and viral nucleocapsid protein was detected in the epithelium of the respective biopsy samples. However, no infectious virions were recovered from any samples. In vitro exposure of SARS-CoV-2 to colonic liquid led to a 4-log-fold reduction of infectious SARS-CoV-2 within 1 hour (P ≤ .05).

Conclusion

Overall, the persistent detection of SARS-CoV-2 in endoscopy samples after resolution of COVID-19 points to the gut as a long-term reservoir for SARS-CoV-2. Since no infectious virions were recovered and SARS-CoV-2 was rapidly inactivated in the presence of colon liquids, it is unlikely that performing endoscopic procedures is associated with a significant infection risk due to undiagnosed asymptomatic or persistent gastrointestinal SARS-CoV-2 infections.