Optimal Insertion Depth for Nasal Mid-Turbinate and Nasopharyngeal Swabs.

Rasmus Eið Callesen,Christian Von Buchwald,Kathrine Kronberg Jakobsen,Michael Papesch,Tobias Todsen,Cecilie Mullerup Kiel,Lisette Hvid Hovgaard

doi:10.3390/diagnostics11071257

Abstract

Millions of people are tested for COVID-19 daily during the pandemic, and a lack of evidence to guide optimal nasal swab testing can increase the risk of false-negative test results. This study aimed to determine the optimal insertion depth for nasal mid-turbinate and nasopharyngeal swabs. The measurements were made with a flexible endoscope during the collection of clinical specimens with a nasopharyngeal swab at a public COVID-19 test center in Copenhagen, Denmark. Participants were volunteer adults undergoing a nasopharyngeal SARS-CoV-2 rapid antigen test. All 109 participants (100%) completed the endoscopic measurements; 52 (48%) women; 103 (94%) white; mean age 34.39 (SD, 13.2) years; and mean height 176.7 (SD, 9.29) cm. The mean swab length to the posterior nasopharyngeal wall was 9.40 (SD, 0.64) cm. The mean endoscopic distance to the anterior and posterior end of the inferior turbinate was 1.95 (SD, 0.61) cm and 6.39 (SD, 0.62) cm, respectively. The mean depth to nasal mid-turbinate was calculated as 4.17 (SD, 0.48) cm. The optimal depths of insertion for nasal mid-turbinate swabs are underestimated in current guidelines compared with our findings. This study provides clinical evidence to guide the performance of anatomically correct nasal and nasopharyngeal swab specimen collection for virus testing.

Highlights

IntroductionTesting is essential for controlling and limiting the spread of coronavirus disease 2019
The clinical specimens obtained are typically tested with either a real-time reverse-transcription polymerase chain reaction (RT-PCR) or the “rapid” antigen tests for SARS-CoV-2 infection [4]
The participants completed a questionnaire prior to the nasopharyngeal swab performed for rapid antigen testing

Summary

Introduction

Testing is essential for controlling and limiting the spread of coronavirus disease 2019. (COVID-19), and millions of people are tested daily during the pandemic [1]. The Center for Disease Control and Prevention (CDC) recommends collecting an upper respiratory specimen for initial SARS-CoV-2 infection testing, and nasopharyngeal swabs are considered the highest-yield sample for respiratory viruses [2,3]. The clinical specimens obtained are typically tested with either a real-time reverse-transcription polymerase chain reaction (RT-PCR) or the “rapid” antigen tests for SARS-CoV-2 infection [4]. There is considerable disagreement in guidelines with respect to the recommended insertion depth of nasopharyngeal swabs [5]. The suggested insertion depth ranges anywhere from 4 to 10 cm [5,6,7,8,9]

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Conclusion