The difference between nasal swab and throat swab

The detection result of nucleic acid of new coronavirus is an important reference for diagnosis and curative effect evaluation of new coronavirus pneumonia. The screening samples for nucleic acid detection mainly come from deep cough sputum or throat swab, which is divided into nasopharyngeal swab and oropharyngeal swab. So, what is the difference between the two?

Pharynges include nasopharynx, oropharynx and throat. Their mucous membranes are continuous and belong to the upper respiratory tract. Nasopharyngeal swab and oropharyngeal swab only have different sampling paths. Oral sampling is oropharyngeal swab and nasal sampling is nasopharyngeal swab.

Because the oropharynx swab can be operated through the opening, it is relatively simple, so it is more commonly used in clinic. However, for those who take oropharyngeal samples, the risk of exposure is higher. Operators often need to face the patient’s mouth. During the collection process, patients are prone to irritation, dry cough, vomiting and other symptoms, which expose the collectors to aerosol carrying viruses. Nasopharyngeal swab has several advantages over oropharyngeal swab. In order to obtain a sufficient number of specimens, they can stay in pharynx for a longer time during sampling, which is why the positive rate is higher than that of oropharyngeal swabs reported in the literature. In addition, patients are well-tolerated, so they can usually undergo topical anesthesia and nasal mucosa contraction first, and skilled samplers can sample patients without anesthesia.