Nucleic acid testing usually collects the following respiratory tract samples

Nasopharyngeal swabs

• Collection site: It reaches the nasopharynx from the nasal cavity. The specific location is the junction between the back of the nasal cavity and the throat. The secretions in this area contain more respiratory epithelial cells. If the virus infects the respiratory tract, it is more likely to be detected in this area.
• Operation method: The medical staff will ask the person being tested to slightly tilt their head back, and then gently insert a slender swab into one nostril, slowly go deep along the nasal cavity wall until resistance is felt, usually insert to a depth approximately equal to the distance from the tip of the nose to the earlobe, rotate the swab several times, and then slowly remove it.

Oropharyngeal swabs

• Collection site: Mainly in the throat area, including the tonsillar crypts, posterior pharyngeal wall and other regions. These areas are also places where respiratory viruses are prone to gather and be infected, and collecting samples from here can effectively detect whether the virus exists.
• Operation method: The person being tested needs to open their mouth wide and make a “ah” sound to fully expose the throat. The medical staff will quickly wipe the bilateral tonsils and posterior pharyngeal wall with the swab, with gentle and rapid movements to avoid touching the tongue and other parts of the mouth to prevent contamination of the sample.

Sputum samples

• Collection method: If the person being tested can cough up sputum independently, it can be directly collected into a sterile container. For some people who cannot cough up sputum independently, it may be necessary to induce sputum to be discharged through atomization inhalation and other methods before collection. Sputum samples contain a large amount of respiratory secretions and cells, and the virus content is relatively high, and the detection accuracy is also relatively high, but the collection difficulty is relatively large, because not everyone can easily cough up qualified sputum.

Bronchoalveolar lavage fluid

• Collection method: This is a more complex sampling method, usually requiring bronchoscopy guidance. The bronchoscope is inserted into the bronchus in the lung, and then an appropriate amount of normal saline is injected into the alveoli, and then the lavage fluid containing alveolar surface liquid and cells is recovered as a detection sample. This type of sample collection method can directly obtain samples from deep in the lung, and has important diagnostic value for detecting some viral infections in the lower respiratory tract, especially when the disease is more severe or the test results of conventional sampling methods are not clear. However, the operation is difficult and has certain risks, and is generally only used when necessary.