nasopharyngeal swab
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{{Infobox diagnostic
| name = Nasopharyngeal swab
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| caption = Nasopharyngeal swab
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| purpose = Diagnosis of certain viral infections
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| MedlinePlus = 003747
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A nasopharyngeal swab is a device used for collecting a sample of nasal secretions from the back of the nose and throat.{{cite web |url=https://medlineplus.gov/ency/article/003747.htm |title=Nasopharyngeal culture |work=MedlinePlus |date=23 March 2020 |access-date=25 March 2020}}{{cite book |url=https://books.google.com/books?id=zmBWAAAAYAAJ |title=The complete equine veterinary manual: A comprehensive and instant guide to equine health |author=Pavord, T. |author2=Pavord, M. |publisher=David & Charles |edition=2nd |page=206 |year=2004 |isbn=9780715318836}} 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 of whooping cough, diphtheria, influenza, and various types of diseases caused by the coronavirus family of viruses, including SARS, MERS, and COVID-19.{{cite book |chapter-url=https://books.google.com/books?id=YP8hBAAAQBAJ&pg=PT97 |chapter=20. Identification of Pathogenic Bacteria |title=Medical Laboratory Technology |author=Junkins, A. |editor=Mukherjee, K.I. |editor2=Ghosh, S. |edition=2nd |volume=2 |publisher=Tata McGraw-Hill |page=515 |year=2010 |isbn=9781259000768}}{{cite web |url=https://www.cdc.gov/pertussis/clinical/diagnostic-testing/specimen-collection.html |title=Specimen Collection |work=Pertussis (Whooping Cough) |publisher=Centers for Disease Control and Prevention |date=18 November 2019 |access-date=25 March 2020}}{{cite journal |title=Comparison of nasal and nasopharyngeal swabs for influenza detection in adults |journal=Clinical Medicine & Research |author=Irving, S.A. |author2=Vandermause, M.F. |author3=Shay, D.K. |author4=Belongia, E.A. |volume=10 |issue=4 |pages=215–8 |year=2012 |doi=10.3121/cmr.2012.1084 |pmid=22723469 |pmc=3494547}}{{cite web |url=https://www.cdc.gov/flu/pdf/freeresources/healthcare/flu-specimen-collection-guide.pdf |title=Influenza Specimen Collection |publisher=Centers for Disease Control and Prevention |date=n.d. |access-date=25 March 2020 |quote=A nasopharyngeal (NP) swab is the optimal upper respiratory tract specimen collection method for influenza testing.}}{{cite book |url=https://books.google.com/books?id=QtjQDwAAQBAJ&pg=PA1083 |title=Henry's Clinical Diagnosis and Management by Laboratory Methods |author=McPherson, R.A. |author2=Pincus, M.R. |publisher=Elsevier |edition=First South Asia |page=1083 |year=2017 |isbn=9788131231272}}{{cite journal |url=https://apps.who.int/iris/handle/10665/331501 |title=Laboratory testing for coronavirus disease (COVID-19) in suspected human cases: Interim guidance, 19 March 2020 |journal=WHO/COVID-19/Laboratory/2020.5 |author=World Health Organization |publisher=World Health Organization |date=19 March 2020 |hdl=10665/331501 |access-date=25 March 2020}}
Procedure
File:Pertussis Testing Video- Collecting a Nasopharyngeal Swab Clinical Specimen.webm
To collect the sample, the swab is inserted in the nostril and gently moved forward into the nasopharynx, a region of the pharynx that covers the roof of the mouth.{{cite journal | vauthors = Marty FM, Chen K, Verrill KA | title = How to Obtain a Nasopharyngeal Swab Specimen | journal = The New England Journal of Medicine | date = 28 May 2020 | volume = 382 | issue = 22 | pages = e76 | doi=10.1056/NEJMvcm2010260 | pmid = 32302471 | doi-access = free }} The swab is then rotated for a specified period of time to collect secretions, then the swab is removed and placed into a sterile viral transport media, which preserves the sample for the subsequent analysis.
Material composition of swab
Similar in concept to the cotton swab, a swab used for nasopharyngeal collection constitutes a narrow stick made of a short plastic rod that is covered, at one tip, with adsorbing material such as cotton, polyester, or flocked nylon. (Some swab handles have been made of nichrome or stainless steel wire.{{cite journal |title=Comparison between nasopharyngeal swab and nasal wash, using culture and PCR, in the detection of potential respiratory pathogens |journal=BMC Research Notes |author=Gritzfeld, J.F. |author2=Roberts, P. |author3=Roche, L. |display-authors=etal |volume=4 |at=122 |year=2011 |doi=10.1186/1756-0500-4-122 |pmid=21489228 |pmc=3084159 |doi-access=free }}) The swab material used for a particular diagnostic application may vary based on the test type. Some research has shown that flocked swabs collect a larger volume of the sample material, when compared to fiber swabs.{{cite book |url=https://books.google.com/books?id=aZp_AwAAQBAJ&pg=PA166 |title=Human Respiratory Viral Infections |editor=Sing, S.K. |publisher=CRC Press |page=166 |year=2014 |isbn=9781466583207}}
Related methods
Slightly different but related is nasopharyngeal aspiration. Rather than depending on a physical swab to catch material from the nasopharynx, aspiration uses a catheter 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. 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.{{cite journal |title=Comparing the Yield of Nasopharyngeal Swabs, Nasal Aspirates, and Induced Sputum for Detection of Bordetella pertussis in Hospitalized Infants |journal=Clinical Infectious Diseases |author=Nunes, M.C. |author2=Soofie, N. |author3=Downs, S. |display-authors=etal |volume=63 |issue=Suppl. 4 |pages=S181–S186 |year=2016 |doi=10.1093/cid/ciw521 |pmid=27838671 |pmc=5106614}}
Diagrams
File:Nose and nasal cavities.png|Diagram of the nasal cavity
File:Diagnosis-image2.jpg|Nasopharyngeal aspiration
File:Pertussis Testing Video- Collecting a Nasopharyngeal Aspirate Clinical Specimen.webm|Collecting nasopharyngeal aspirate
File:Infektionsschutzzentrum im Rautenstrauch-Joest-Museum, Köln-6313 (cropped).jpg
File:Prueba COVID.webm|Video of a nasopharyngeal swab test for COVID-19
See also
References
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