With the development of the new coronavirus, many institutions currently use the method of collecting nasopharyngeal swabs for viral nucleic acid testing. This method is simple and easy to implement, and is easier to popularize. It is an effective method for rapid diagnosis of respiratory virus infection or carrying status.
Today, the Department of Otorhinolaryngology, Head and Neck Surgery of the Air Force Special Medical Center explores the key points that need to be paid attention to in the collection process from an anatomical point of view, in order to improve the quality of detection, reduce the discomfort of the population, and avoid the occurrence of adverse events.
First of all, we understand the structure of the hypopharyngeal area. The pharynx includes the nasopharynx, oropharynx, and laryngopharyngeal. The mucous membranes of the three are continuous and belong to the upper respiratory tract. The nasopharyngeal swab and the oropharyngeal swab are only different in the sampling path. Oral sampling is an oropharyngeal swab, and nasal sampling is a nasopharyngeal swab.
Next, let’s explore the secrets of the nasopharynx!
On the inner and outer side walls of the nasal cavity, there are three bony turbinates protruding from the nasal cavity, arranged in a trapezoid shape, and the free edges are all hanging inward and downward, called the upper turbinate, middle turbinate, and inferior turbinate.
There is a gap-like space outside and under each turbinate, called upper nasal passage, middle nasal passage and lower nasal passage. The common long and narrow space between the turbinates and the nasal septum is called the common nasal passage. There is a superficially dilated posterior nasal venous plexus near the nasopharynx behind the lateral wall of the lower nasal passage, which is called the nasal-nasopharyngeal venous plexus, which is the most common site for bleeding in the back of the nasal cavity.
The nasal septum deviates from the midline or is irregularly deviated, which may cause nasal dysfunction, such as nasal congestion and epistaxis.
What should medical staff pay attention to when collecting nasopharyngeal swabs?
When collecting a nasal swab, the subject needs to tilt his head back. The swab is not in the direction of the nostrils, but perpendicular to the face, and enters from the common nasal passage. Press the swab down as far as possible, close to the lower wall of the nasal cavity, and take it out vertically when it enters the nasopharynx when there is an obvious "wall-hit feeling".
During the collection, if you encounter resistance or the subject feels obvious pain, do not enter violently. The swab will be withdrawn later. At the same time, try to enter after slightly adjusting the angle of the sagittal plane.
When nasopharyngeal sampling, the operator can stand behind the subject without looking directly at the mouth, and there is basically no pharyngeal reflex, the tolerance is good, and the exposure risk is relatively low. Individual subjects may have sneezing reflexes after taking samples and should be covered with elbows or paper towels immediately. A small number of subjects may have a slight nosebleed after sampling. Generally, they can stop on their own. If necessary, use a cotton swab with epinephrine to slightly shrink the bleeding site. When sampling a nasopharyngeal swab, you can stay in the nasopharynx for a longer period of time in order to obtain a more adequate sample.
When sampling the throat swab, the subject opened his mouth to make a long “ah” sound, and a tongue depressor was used if necessary. The swab gently and quickly wipes the lateral wall of the pharynx and the back wall of the pharynx several times. Since the oropharyngeal swab can be operated by opening the mouth, it is relatively simple, so it is more commonly used clinically. However, when sampling through the oropharynx, the operator often needs to face the oral cavity of the subject, and the risk of exposure is high.
Studies have shown that the positive rate of nasal swab specimens is higher than that of throat swab specimens, that is, the sensitivity of virus nucleic acid detection of nasal swabs is higher than that of throat swabs. In clinical practice, priority should be given to nasal swabs for virus nucleic acid detection specimen sampling. This can more reduce missed diagnoses, and at the same time reduce the possible exposure of medical staff to the virus.
The nasal cavity and oropharynx are the main tracts for breathing and swallowing. They are exposed to the environment. During nucleic acid collection, it is inevitable to contact the mucosa of the upper respiratory tract. At the same time, it will stimulate the nasal cavity or throat reflex stress and cause the subject to sneeze and cough. , Retching, etc., causing droplets or the aerosols produced by them to suspend in the air, significantly increasing the risk of cross-infection. If a subject with an incubation period collects without knowing it, it will have a source of infection and a route of transmission, which can easily lead to virus infection.
Therefore, while doing a good job of protection during the detection, it is necessary to improve the detection technology, obtain good cooperation, and reduce the occurrence of adverse events in the collection. In case of abnormalities, please go to the Otorhinolaryngology Head and Neck Surgery Department in time for treatment under the guidance of a professional doctor.