Complications of Nasopharyngeal Swabs and Safe Procedures for COVID-19 Testing Based on Anatomical Knowledge

Abstract

Nasopharyngeal swabs have been widely to prevent the spread of coronavirus disease 2019 (COVID-19). Nasopharyngeal COVID-19 testing is a generally safe and well-tolerated procedure, but numerous complications have been reported in the media. Therefore, the present study aimed to review and document adverse events and suggest procedural references to minimize preventable but often underestimated risks. A total of 27 articles were selected for the review of 842 related documents in PubMed, Embase, and KoreaMed. The complications related to nasopharyngeal COVID-19 testing were reported to be rarely happened, ranging from 0.0012 to 0.026%. Frequently documented adverse events were retained swabs, epistaxis, and cerebrospinal fluid leakage, often associated with high-risk factors, including severe septal deviations, pre-existing skull base defects, and previous sinus or transsphenoidal pituitary surgery. Appropriate techniques based on sufficient anatomical knowledge are mandatory for clinicians to perform nasopharyngeal COVID-19 testing. The nasal floor can be predicted by the line between the nostril and external ear canal. For safe testing, the angle of swab insertion in the nasal passage should remain within 30° of the nasal floor. The swab was gently inserted along the nasal septum just above the nasal floor to the nasopharynx and remained on the nasopharynx for several seconds before removal. Forceful insertion should be attempted, and alternative examinations should be considered, especially in vulnerable patients. In conclusion, patients and clinicians should be aware of rare but possible complications and associated high-risk factors. The suggested procedural pearls enable more comfortable and safe nasopharyngeal COVID-19 testing for both clinicians and patients.

Keywords: COVID-19 Testing; Complications; Nasopharyngeal Swab; Procedural Reference; Risk Factors.

Fig. 1. Basic (A) anatomical and (B, C) procedural background information for a safe nasopharyngeal swab. (A) The blue horizontal line starts from the anterior nasal spine and ends on the external auditory canal. Nasopharyngeal swabs should be performed within 30° from the blue to redline. Clinicians should be cautious not to (B) hold the swab inappropriately and are recommended to (C) grip the swab appropriately. (B) The inappropriate way to hold the swab causes difficulty to enter the safety zone within 30° after passing the anterior nasal spine.

1: cribriform plate; 2: anterior wall of sphenoid sinus; 3: anterior nasal spine; 4: nasal floor. Reproduced from the article of Mistry et al. (2021).

Fig. 2. The ideal procedural steps to obtain a nasopharyngeal swab specimen for coronavirus disease 2019 testing. (A) Before testing, the clinician can predict the full depth of insertion by measuring the length between the nostril and the external ear canal. (B) Insert the swab into the nostril no more than 3 cm parallel to the nasal bridge until reaching the anterior nasal spine. After passing the anterior nasal spine, (C) raise the hand that holds the swab about 70° upward and (D) delicately insert the swab along the nasal septum just above the nasal floor to the target area, nasopharynx. The swab should be stayed on the target area for several seconds and gently pull back the swab while rotating it within fingers, not making big circles with entire hands, to avoid excessive irritation (The pictures were demonstrated by the authors, Moon JW and Chae S with full agreement for publication).