Pharyngeal swab specimens include two types, nasopharyngeal swabs and oropharyngeal swabs. In terms of specimen quality, nasopharyngeal swabs are slightly superior to oropharyngeal swabs, but in terms of sampling experience, oropharyngeal swabs are, in turn, superior to nasopharyngeal swabs.
Many factors affect the accuracy of sample testing, including sampling site, sampling technique, cooperation of the sampled person, and laboratory testing technique. Nasopharyngeal and oropharyngeal swabs also differ in collection methods and sample load.
Samples are Collected From Different Part
Oropharyngeal Swab: the sample is taken at the back of the throat
Nasopharyngeal Swab: sampling requires extending the nasopharyngeal swab inside the nasal cavity and slowly rotating it to reach deep into the nasal cavity.
People Feel Differently
Oropharyngeal Swab: You can do it by opening your mouth wide, and some people may have a dry heaving sensation.
Nasopharyngeal Swab: It will be uncomfortable for people, especially those who suffer from the curved septum and enlarged turbinates.
Different Exposure Risks
Oropharyngeal Swabs: The sampler needs to be directly in front of the patient, and the patient may experience irritating coughing and vomiting when the swab enters the mouth, which puts the operator at risk of infection.
Nasopharyngeal Swab: The patient does not have a gag reflex during sampling, and the risk of exposure to the sampler is lower.
Different Positive Detection Rates
When sampling with an oropharyngeal swab, the patient will have a gag reflex, and the swab will have difficulty staying in the throat. Combined with eating and swallowing motions, it will reduce the enrichment of the virus in the oropharynx and affect the positive detection rate.
Nasopharyngeal swabs can stay deeper in the throat longer to obtain a sufficient sample, so the positive detection rate is relatively higher.
Nasopharyngeal swabs should be avoided for the following groups
Patients with severe allergic rhinitis, intra-nasal abnormalities, recent nasal bleeding, patients who have undergone nasal surgery for no more than three months, patients with hemophilia, and patients on long-term anticoagulants.