A nasal (or nasopharyngeal) swab is used to diagnose upper respiratory tract infections, such as whooping cough and COVID-19. It is a quick test that may feel a little uncomfortable but is not painful.
In this test, secretions from the back of your nose and upper throat are collected using a swab. Sometimes, a suction device may be used to gently remove the secretions. This is known as a nasal (or nasopharyngeal) aspirate.
The secretions are sent to a laboratory where they are grown. This makes it easier to identify which viruses, bacteria or fungi are present. The results are sent back to your doctor who will use them to help diagnose what germs could be causing your symptoms.
How is a nasal swab done?
To do a nasal swab, a small, soft-tipped swab will be inserted into one or both of your nostrils and twirled a few times until it is covered in secretions. Only a single swab is taken for COVID-19 testing.
The swab will be inserted quite a way in to get to the area that will give the best result. This may be a little uncomfortable but should not be painful.
Note that although a nasal swab is the preferred option for COVID-19 diagnosis, sometimes a throat swab is used.
How is a nasal aspiration done?
If your doctor uses the nasal aspiration method, a small tube will be inserted into your nostril. This tube is connected to a suction device, which gently removes secretions from your nose. This will be repeated on the other nostril.
Learn more
The following links provide further information about nasal swab testing. Be aware that websites from other countries may have information that differs from New Zealand recommendations.
Credits: Health Navigator Editorial Team. Reviewed By: Gwenda Lawrence, medical laboratory scientist, Auckland
Last reviewed: 16 Mar 2020
Information for healthcare providers on nasal swab test
The content on this page will be of most use to clinicians, such as nurses, doctors, pharmacists, specialists and other healthcare providers.
Nasopharyngeal swab
A nasopharyngeal swab is used to sample secretions from the back of the nose and upper throat to help identify what pathogens are present that could be causing symptoms or disease.
A nasopharyngeal swab or aspirate is needed for Polymerase Chain Reaction (PCR) testing, one of the best ways to diagnose pertussis. PCR is "a molecular technique used to detect DNA sequences of the Bordetella pertussis bacterium and unlike culture, does not require live bacteria present in the specimen." (Centers for Disease Control and Prevention, US).
Specimens for PCR testing should be obtained by aspiration or swabbing the posterior nasopharynx.
Throat swabs and anterior nasal swabs are not suitable as they have much lower rates of DNA recovery.
PCR testing needs to be done within the first 2–4 four weeks. After this time, there is less bacterial DNA present and a higher rate of false-negative results.
It is important the test is performed correctly and the person taking the sample wears appropriate safety gear to reduce their exposure.
This includes safety glasses, paper mask and gloves.
Not all community labs will collect a nasopharyngeal swab. Check your local services.
The following video demonstrates the proper techniques for collecting and transporting secretions using a nasal swab.
(Video: Centers for Disease Control and Prevention, US)
The following video demonstrates proper techniques for collecting and transporting secretions from the nose obtained by aspiration.
(Video: Centers for Disease Control and Prevention, US)
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