Optimal Insertion Depth for Nasal Mid-Turbinate and Nasopharyngeal Swabs

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.

Rapid screening of SARS-CoV-2 infection: Good performance of nasopharyngeal and Nasal Mid-Turbinate swab for antigen detection among symptomatic and asymptomatic individuals

“…On the other hand, another report by Másia et al [ 16 ] informed that the Panbio test performance was not satisfactory for the nasal swab sampling and its sensitivity was much lower with this type of sample than with the nasopharyngeal one (44.7% vs. 60.5%, respectively). Discrepancies in diagnostic performance of this research compared to our results could be due to multiple reasons, including different clinical and epidemiological scenarios in which both studies were performed; variations in sampling techniques and handling procedures, which depends on health care personal in charge of sample collection in each study, such as different depths of insertion for nasal mid-turbinate swab and swabbing one or both nostrils [ 17 ]), inadequate quality of the sample collected, etc. Furthermore, because the readout of this type of assays is by visual inspection, results may be subjective, especially when bands are faint or partial.…”

Clinical Accuracy of Instrument-Read SARS-CoV-2 Antigen Rapid Diagnostic Tests (Ag-IRRDTs)

“…For example, measurement temperature may also affect Ag-IRRDT sensitivity and specificity results [ 58 ], but only few reports include their measuring temperature ranges. Similarly, a lack of evidence to guide optimal nasal swab testing can increase the risk of false-negative test results [ 59 ]. Whether SARS-CoV-2 antigen-detection using a rapid test with self-collected nasal swab or professional-collected nasopharyngeal swab makes a difference can be another issue [ 60 ].…”

Valid and Reliable Assessment of Upper Respiratory Tract Specimen Collection Skills during the COVID-19 Pandemic

“…Moreover, in a clinical setting it will not be possible for the rater to see the intraoral OPS sampling technique which we instead could visualize with a video endoscope in the simulated setting for more complete assessment of sample technique (see Figure 1). A critical part of the NPS specimen collection is whether the swab reach the nasopharyngeal wall which require an insertion length between 8-11 cm [9]. However, the rater could not directly visualize if the swab reached the nasopharyngeal wall during the test participants performance on the NPS simulator model.…”

“…However, the rater could not directly visualize if the swab reached the nasopharyngeal wall during the test participants performance on the NPS simulator model. Nevertheless, as the model has known realistic anatomy proportions it could be seen if the swab was inserted to high and trapped before at the midturbinates instead, see Figure 1 [9,17].…”

“…A MCQ and a checklist for upper respiratory tract specimens' collection skills (URTS) were developed as an objective structured clinical examination (OSCE) format test with content evidence obtained through two steps. First, we used the technical guide from the WHO together with an additional literature review to ensure the contents of the URTS MCQ, and the URTS checklist followed international recommendations [3,[8][9][10][11][12][13][14][15][16]. We then recruited a multidisciplinary board of experts constituted by a consultant in rhinology (CvB), a consultant in head and neck surgery (JM), a consultant in infectious disease (TB), a microbiology specialist (NK), and a medical education scientist (MT) to review the content of each item on the checklist.…”