Examining COVID-19 polymerase chain reaction testing before endoscopy

Aug. 15, 2020

The first cases of COVID-19 in the United States were diagnosed in early March 2020. Mayo Clinic, like many other centers across the country, had to limit endoscopic procedures to emergent indications only. During the initial weeks of the pandemic, testing for COVID-19 was provided through local health departments only, and turnaround time ranged between four and 10 days.

On March 24, Mayo Clinic Laboratories started performing real-time polymerase chain reaction (PCR) testing in-house, with results available within three to four hours. This was possible through the leadership of Mayo's clinical laboratory using a combination of commercially acquired and internally developed reagents. A week later, a policy was implemented to test all patients within 48 hours before having an outpatient endoscopy or surgical procedure.

Seeking a data-driven path forward

There is no consensus on what constitutes an emergent endoscopy during the COVID-19 pandemic and what endoscopic procedures can be postponed. Furthermore, little information on the clinical accuracy of the test was available to help guide resumption of the clinical practice, while keeping patients and health care staff safe. To better understand the safety and financial implications of pre-procedure PCR testing, it was decided to create a computer model to compare different approaches for COVID-19 testing in patients requiring semi-urgent and elective endoscopies.

The main objective was to compare the number of endoscopies that could be performed under three different strategies that incorporate PCR testing. We first modeled the impact of this policy at Mayo Clinic in Florida and then extrapolated to all cases performed in the United States. The secondary objective was to identify clinical factors under which different strategies are more effective and safer to resume endoscopy workflow.

The study, published in the journal Gastrointestinal Endoscopy, compared three strategies: Perform endoscopy only for urgent indications, for urgent and semi-urgent indications, and finally endoscopy for all indications. We used available data on costs at our own institution as well as Medicare data. Assuming personal protective equipment is available, we calculated that universal PCR testing for semi-urgent and all procedures across the United States would cost $13 million and $64 million per week, respectively; would return to providers $165 million and $767 million per week, respectively; and would risk infection of 65 and 325 health care workers on a weekly basis, respectively.


This study argues that the implementation of universal COVID-19 PCR testing of patients is a sensible strategy to resume endoscopy practice. The "test all endoscopy candidates" was the preferred strategy. April data from Duval County, Florida, was used to calculate that the program could be implemented with a very high negative predictive value and few health care workers exposed, approximately one exposure every three months.

We conclude that testing is a critical piece of an integral strategy to reopen our endoscopy practice. Our findings are presented in the context of a four-phase road map to reopen endoscopy centers, along with personal protective equipment, telemedicine evaluations and longitudinal epidemiologic surveillance.

For more information

Corral J, et al. COVID-19 polymerase chain reaction testing before endoscopy: An economic analysis. Gastrointestinal Endoscopy. In press.