Antigen detection test: how to collect pharyngeal specimen correctly - part 1

The problem of false negative detected by COVID-19 throat swab is plaguing the medical personnel who fight in the front line of epidemic prevention and control. How to solve this problem?

What is the key to the accuracy of pharyngeal swab nucleic acid test specimen collection? There are three main factors:

Depth of throat swab collection?

How long does the pharyngeal swab contact the mucosa?

Pharyngeal swab sampling "point to point" or wipe?

Oropharyngeal swab collection tips

1. Preparation before sampling: give the sampling tube to the patient, let the patient take the tube, inform the patient that there may be discomfort during sampling, and inform the patient that the tube needs to be held vertically, so that the patient can concentrate on the tube, so as to reduce the discomfort caused by nasopharyngeal stimulation during sampling.

2. Body position during sampling: take the sitting or semi sitting position, slightly tilt the patient's head, open his mouth, and rest his head against the wall or against the back of the chair.

3. Standardize the sampling operation: press the patient's tongue with a tongue depressor and order a long "ah -" sound. The pharyngeal swab shall be used for "up and down three back and forth fast wiping" on the bilateral pharyngeal tonsils of the patient and "left and right three back and forth fast wiping" on the posterior pharyngeal wall to avoid contacting the tongue, teeth and gums. In case of discomfort, quit and have a rest and try again.

4. Precautions: drinking water before oropharyngeal swab detection will dilute the virus attached to the pharynx, especially drinking hot water will inhibit the activity of the virus. In order to improve the accuracy of pharyngeal swab nucleic acid detection, ask the patient not to drink water 15-30 minutes before detection, so as to ensure the high accuracy of pharyngeal swab nucleic acid detection. Patients with good throat exposure are not recommended to have long hair "ah -" to reduce the occupational exposure risk of the sampler.