What Is a Nasopharyngeal Swab?

A nasopharyngeal swab is a specimen collection tool used to sample cells in the nasopharynx, the upper region of the throat. If a patient has what appears to be an upper respiratory infection, the doctor may use a swab to collect a sample for testing, especially if the patient also has a fever. In a lab, technicians can check for common infectious agents, including potential pathogens like swine flu. This testing can be uncomfortable for patients, but allows for quick identification of serious respiratory disease, especially conditions that might necessitate isolation or infection precautions to protect other patients.

The swab consists of a polyester puff on the end of a flexible plastic probe. Cotton and other natural materials cannot be used in a nasopharyngeal swab because they can contain impurities that might interfere with testing. Typically it comes in a sealed package which the care provider can set up next to the patient along with a specimen container that includes a medium designed to keep any cells and microorganisms alive for evaluation.

Typically, gloves and facial protection are worn for a nasopharyngeal swab collection. Protecting the face is a precaution in case the patient has an infectious respiratory disease. To collect the sample, the swab is gently inserted into the nose, pushing straight back to reach the nasopharynx. This is usually uncomfortable and patients may jerk or pull away; for this reason, they are sometimes asked to sit with their heads against a wall or pillow to suppress this reaction.

Once the nasopharyngeal swab is all the way in, the care provider can briefly spin it to collect a mixture of cells, withdraw it, and drop it in the specimen collection container. This should be forwarded to a lab for testing immediately. If it waits or is not stored in cool conditions, there is a risk of killing organisms that might be present in the sample, which could result in a false negative test result. Patients can expect results in varying amounts of time, depending on how many samples the lab has to process.

Testing can scan for a variety of common organisms. In a region where an outbreak of infectious disease is occurring, the nasopharyngeal swab may be flagged to test for an organism like swine flu. Test results can be used to direct treatment for the patient. They can also help epidemiologists trace the movement of disease through a community, which can be valuable for controlling outbreaks.