In this article an infectious diseases pharmacist provides information and resources on nasopharyngeal sampling.
Last Updated: 28 April 2020
Nasopharyngeal (NP) samples are used for a multitude of different diagnostic tests. As an infectious diseases (ID) pharmacist that typically practices in the adult, inpatient setting, my perception of the accuracy of these tests is biased by influenza season. Depending on the specific type of test (i.e., antigen detection versus nucleic acid amplification), the platform that runs the test, as well as which pathogen the test is looking for, sensitivities can vary substantially [1,2].
When a test is positive, the information is helpful in determining an appropriate pathogen. However, when negative, I often question the results and have to correlate the results with the clinical picture . In my opinion, as well as the opinion of some others that I know, a significant contributor to false negative results with tests that require a NP sample is because the test itself is uncomfortable for the patient and can be uncomfortable to administer correctly .
Given my experiences with NP swabs over the last few years for respiratory viruses as well as the U.S. Department of Health and Human Services (HHS) expansion of pharmacists as “covered persons” under the Public Readiness and Emergency Preparedness Act (PREP Act) to order and administer COVID-19 tests, I wanted to share some quick notes on the administration of NP tests .
The instructions provided here are my interpretation of a compilation of resources including guidance from the Centers for Disease Control and Prevention on NP swabs collected for influenza and SARS-CoV-2 testing, instructions from the New England Journal of Medicine, point of care testing guidance from the National Community Pharmacists Association, as well as several medication YouTube videos [6-13]. References were obtained through searches of national guidelines, national healthcare organizations, government guidance, and other reputable sources. The author and host of this content do not provide this for direct application to patient care, as explained in our terms. If intending to implement NP swabs as a pharmacist (especially in the community setting) we direct you to reference national guidance for specific infection personal protective equipment (PPE) and testing recommendations, your respective state board of pharmacy rules and regulations, FDA Emergency Utilization Authorizations, as well as the need for Clinical Laboratory Improvement Amendments of 1988 (CLIA) waivers [14-15].
NP samples are considered biohazards and have additional applicable regulations through CLIA. Anyone handling samples should take note of the additional guidance requested by five professional healthcare organizations for information regarding broad implementation of SARS-CoV-2 testing . As mentioned earlier, the steps below are the author’s interpretation and insight for administering a NP swab. This is provided for information only to help understand what elements are important in NP sampling. These instructions are not a replacement for clinical judgement and do not serve as an official recommendation for practice.
Here is my take on appropriate nasopharyngeal sampling…
Steps to Consider for Administering a Nasopharyngeal (NP) Swab
1. Gather testing supplies and don appropriate PPE per CDC guidance.
2. Counsel the patient what the test will entail and that the test will create pressure and is commonly uncomfortable for patients. It is normal for patients to tear up toward the end of the procedure. This will help them to understand what to expect as well as possibly mitigate unnecessary movements. You can also advise patients that during the procedure, it can help for patients to close their eyes in order to be more comfortable and prevent sneezing. Make sure to receive consent from the patient that they wish to proceed with the procedure.
3. Prior to starting, have the patient blow their nose into a tissue and discard the tissue.
4. Have the patient sit down in a chair. The patient will likely have a mask on. The patient should either remove their mask or leave the mask on but lower it so that it only covers the mouth during the procedure.
5. Tilt the patient’s head back so that you can more clearly appreciate the patient’s nostrils.
a. Look for nasal obstructions or a deviated septum. If present, apply the NP swab to the opposite nostril. If there is abnormal anatomy in both nostrils, refer to the CDC website for alternative testing options including the oropharyngeal specimen, the nasal mid-turbinate swab, an anterior nares swab, and a nasopharyngeal wash/ aspirate.
6. Either brace the patient’s head with the hand opposite from the one that you intend to do the NP swab with (commonly your non-dominant hand) or have the patient’s head rest on a wall. This test is uncomfortable for the patient when done correctly so they may jerk or move their head. Bracing their head helps prevent unnecessary movements during the procedure.
7. Stand out of the direct path from an unexpected sneeze or cough from the patient to avoid further exposure to the virus. This can be accomplished by standing slightly off-set from the patient.
8. Gather your sterile swab and hold it in your dominant hand as if holding a pen with your thumb, index finger, and middle finger.
9. Insert the NP swab into the patient’s nostril in a horizontal direction along the nasal floor until you feel resistance. Do not be surprised if it takes inserting the swab around 2 inches before resistance is felt in an adult. This roughly correlates to the beginning of the patient’s ear.
a. The swab should NOT be pointed up toward the patient’s eye or brain but instead should be approximately perpendicular to the patient.
b. If resistance is felt too early, consider administering the test in the opposite nostril.
10. Once resistance is met, you are at the nasopharynx. Leave the swab in the patient’s nostril for a few seconds as you rotate the swab in order to pick up more virus particles and secretions. Do not let go of the NP swab while swirling the NP swab.
11. Carefully remove the NP swab from the patient and insert the swab directly into the viral transport media to prevent further contamination.
12. If the swab sticks out above the viral transport media collection device, there should be a line or groove where you can press the swab against the container in order to break off the end and leave the swab in the viral transport media. Be careful to prevent spilling of the viral transport media and sample.
13. Place the swab in a biohazard bag or a designated storage device as determined by the specific test.
14. Have the patient re-apply their mask.
15. Doff PPE as appropriate for the clinical setting (i.e., you probably still want to have a face mark on but may no longer need a gown.
• NEJM YouTube video: https://www.youtube.com/watch?v=DVJNWefmHjE
• NEJM video: https://www.nejm.org/doi/full/10.1056/NEJMvcm2010260
• COVID-19 specific YouTube video: https://www.youtube.com/watch?v=syXd7kgLSN8
1. Uyeki TM, Bernstein H, Bradly JS, et al. Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenza. Clin Infect Dis. 2019;68(6):e1-47. DOI: 10.1093/cid/ciy866
2. Merckx J, Wali R, Schiller I, et al. Diagnostic Accuracy of Novel and Traditional Rapid Tests for Influenza Infection Compared with Reverse Transcriptase Polymerase Chain Reaction: A Systematic Review and Meta-Analysis. Ann Intern Med. 2017;167:394-409. DOI:10.7326/M17-0848
3. Centers for Disease Control and Prevention. Algorithm to assist in the interpretation of influenza testing results and clinical decision –making during periods when influenza viruses are circulating in the community. Updated: March 4, 2019. Accessed April 24, 2020.
6. Centers for Disease Control and Prevention. Interim Guidelines for Collecting, Handling, and Testing Clinical Specimens from Persons for Coronavirus Disease 2019 (COVID-19). Updated April 14, 2020. Accessed April 17, 2020.
16. American College of Clinical Pharmacy, Society of Infectious Diseases Pharmacists, Infectious Diseases Society of America, The Society for Healthcare Epidemiology of America, The Pediatric Pharmacy Association. Response to HHS Statement on Authorizing Licensed Pharmacists to Order and Administer COVID-19 Tests. Published April 16, 2020. Accessed April 16, 2020.
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