A nasal (or nasopharyngeal) swab is used to diagnose upper respiratory tract infections, such as whooping cough. It is a quick, painless test that can be completed in your doctor's office.
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 on a culture. 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 conduct a nasal swab, your doctor will insert a small, soft-tipped swab into each of your nostrils and twirl it a few times until it is covered in secretions. This may be a little uncomfortable but should not be painful.
The following video demonstrates the proper techniques for collecting and transporting a secretions collected by using a nasal swab.
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 each nostril.
The following video demonstrates proper techniques for collecting and transporting a secretions from the nose obtained by aspiration.
(Video source: Center for Disease Control)
Nasopharyngeal aspirate handout Medline Plus (US)
Surveillance manual's chapter on pertussis – laboratory testing
Best practices for health care professionals on the use of Polymerase Chain Reaction (PCR) for diagnosing pertussis Center for Disease Control (US)