Anasopharyngeal swab is a device used for collecting a sample ofnasal secretions from the back of thenose andthroat.[1][2] The sample is then analyzed for the presence of organisms or other clinical markers for disease. This diagnostic method is commonly used in suspected cases ofwhooping cough,diphtheria,influenza, and various types of diseases caused by thecoronavirus family of viruses, includingSARS,MERS, andCOVID-19.[3][4][5][6][7][8]
To collect the sample, the swab is inserted in thenostril and gently moved forward into thenasopharynx, a region of the pharynx that covers the roof of the mouth.[9] The swab is then rotated for a specified period of time to collect secretions, then the swab is removed and placed into a sterileviral transport media, which preserves the sample for the subsequent analysis.[5][6]
Similar in concept to thecotton swab, a swab used for nasopharyngeal collection constitutes a narrow stick made of a short plastic rod that is covered, at one tip, withadsorbing material such as cotton, polyester, or flocked nylon. (Some swab handles have been made ofnichrome or stainless steel wire.[3][10]) The swab material used for a particular diagnostic application may vary based on the test type. Some research has shown thatflocked swabs collect a larger volume of the sample material, when compared to fiber swabs.[7][11]
Slightly different but related is nasopharyngeal aspiration. Rather than depending on a physical swab to catch material from the nasopharynx, aspiration uses acatheter that is attached to a syringe. As with the swab method, the catheter is placed into the nostril and gently advanced to the nasopharynx, where approximately one to three milliliters of saline are introduced, followed by immediate re-aspiration of the saline—along with cells and secretions—back into the syringe.[7] This aspiration method is often used when 1. the patient is an infant or elderly and 2. when the method is indicated as effective for a test type.[6][12]
^abc"Influenza Specimen Collection"(PDF). Centers for Disease Control and Prevention. n.d. Retrieved25 March 2020.A nasopharyngeal (NP) swab is the optimal upper respiratory tract specimen collection method for influenza testing.
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