Recently, a few more patients with new crowns have been detected in China, and we have conducted substantial nucleic acid testing in cities where patients with new crowns have appeared, thus the need for nasopharyngeal swab collection testing has increased significantly.

Nasopharyngeal swab sampling is a common clinical operation, which is important for the diagnosis of respiratory tract infections, and there are many factors affecting the sampling process, if the operation is not standardized, it may directly affect the test results, and even lead to clinical leakage and misdiagnosis. And irregularities in operation can also increase the risk of exposure to infection for medical personnel.

The use of nasopharyngeal swabs to collect mucosal surface specimens from the respiratory tract is a common clinical practice used to assess the presence of respiratory viral or bacterial infections in adults and children.

The collection of nasopharyngeal swabs for nucleic acid testing is an important test in the diagnosis of neocoronavirus.

It can be performed in patients without specific contraindications to nasopharyngeal swab collection, and clinicians should exercise caution if the patient has a recent history of nasal trauma or surgery, or has a significant deviation of the nasal septum, or a history of chronic nasal tract obstruction and severe coagulation disorders.

Nasopharyngeal swabs are special long flexible stems made of plastic or metal with tips made of polyester, rayon or flocked nylon.

It is necessary to ensure that all sampling tubes are labeled prior to the operation and the appropriate application form needs to be filled out before the operation begins.

When collecting specimens related to novel coronaviruses, it is important to follow the respiratory and exposure precautions established by the relevant agencies and to properly wear personal protective equipment.

All patients undergoing novel coronavirus testing should wear a mask. Sampling personnel should wear appropriate personal protection as required.

Ask the patient to remove the mask and blow the nose with a tissue in order to remove excess secretions from the nasal cavity before collecting the specimen.

Remove the swab from the package and have the patient's head tilted back slightly so that the swab can more easily pass through the nasal cavity to the nasopharynx. The patient is asked to close the eyes to alleviate the slight discomfort of the procedure.

Gently insert the pharyngeal swab along the nasal septum until a sensation of resistance indicates that the swab has reached the base of the nasopharynx.

It is important to note that the pharyngeal swab should be inserted parallel to the palate and that if the swab encounters resistance when passing through the nasal tract, it is necessary to back off the swab and attempt to re-enter at a different angle.

The insertion depth of the swab should be equal to the distance from the nostril to the external opening of the ear. The Centers for Disease Control and Prevention (CDC) recommends that the swab should be left in place for a few seconds after reaching the base of the nasopharynx to allow the tip of the swab to absorb secretions, and then slowly removed while rotating the swab.

Open the sampling tube and insert the swab into the sampling tube. Depending on the swab, some will require the swab to be broken from the groove, and some will require it to be placed in the original package.

Most respiratory viruses replicate primarily in the ciliated columnar epithelial cell sites of the posterior nasopharynx, and the ciliated epithelial cells of the anterior nostril and oropharynx, which are also the sites of most viral replication.

Therefore, pharyngeal swabs are usually collected by both nasopharyngeal and oropharyngeal swabs, and the pathogen detection rate of nasopharyngeal swabs is higher than that of oropharyngeal swabs (but this is based on the premise that nasopharyngeal swabs can be performed properly and standardized), so nasopharyngeal swabs are generally recommended.

Nasopharyngeal swabs can be tested for antigens, nucleic acids, or bacterial cultures (e.g., pertussis), but because the requirements for nasopharyngeal swabs are higher than those for oropharyngeal swabs, they are not actually given clinical attention.

Key points to note during the collection of nasopharyngeal swabs are as follows.

1. The patient needs to blow his nose first
(This step is very important!!!)

This will reduce the contamination and interference of nasal secretions and ensure the quality of the specimen.

Take pertussis nasopharyngeal swab collection as an example, there were clinical experiments before, did not blow off the nose and then sampling, the result is that the nasopharyngeal swab inoculated within a few days after the culture dish full of miscellaneous bacteria, so that even if there is pertussis bacilli will be affected by the miscellaneous bacteria.

2. The direction of swab entry should be parallel to the palate

When performing the operation, the tip of the pharyngeal swab needs to be directed toward the earlobe, not toward the top of the head.

In clinical practice, when taking specimens, many beginners have the tip of the pharyngeal swab facing the direction of the top of the head. Since bacteria and viruses are mostly parasitic in the bottom of the nasopharynx, if the nasopharyngeal swab enters in the wrong direction, it is difficult to reach the bottom of the nasopharynx, and the positive rate will be significantly reduced.

3. Swab entry depth needs to reach the bottom of the nasopharynx

The entry depth of pharyngeal swab is equivalent to the distance from the tip of the nose to the earlobe. If the tip of the pharyngeal swab faces the top of the head in actual operation, the entry depth of the pharyngeal swab will be significantly insufficient.

4. Do not forcefully and violently insert

If the pharyngeal swab encounters resistance in the process of entering along the earlobe, it is necessary to adjust the direction and rotate slightly into it instead of forcibly and violently inserting it to avoid damage. Until it reaches the bottom of the nasopharynx, there is a feeling of resistance to hit the wall.

5. When the feeling of hitting the wall appears, the swab stays for a few seconds and rotates and withdraws (no turning back without hitting the wall)

Experience the feeling of hitting the wall suggests that the nasopharyngeal swab has reached the bottom of the nasopharynx, at this time, the nasopharyngeal swab needs to stay at the bottom of the nasopharynx for 10~15 seconds, so that the swab can fully contact the secretions at the bottom of the nasopharynx and adsorb more pathogens.

However, as it is more difficult for children to cooperate, the swab is usually required to stay at the bottom of the nasopharynx for a few seconds without rotating (although theoretically the longer the stay the better, and rotating a few turns is better), and then the swab is withdrawn while rotating. This reduces the irritation to the child and also satisfies the sampling effect at the same time.

6. Aluminum metal swab is safer for children

Since children are obviously less cooperative than adults in operation, this aluminum metal swab is more flexible and will not break in operation, while plastic swabs have been broken in operation residual cases in the nasopharynx of children. Therefore, perhaps aluminum metal swabs are more suitable for pediatric patients.

Choice of swab material and sampling site.

(1) The choice of material of the nasopharyngeal swab and the sampling site of the specimen need special attention on the effect of the examination results.

(2) The choice of swab material varies depending on the test method and the characteristics of the pathogen.

If.

(3) If culture and PCR testing are performed at the same time, swabs made of dacron or nylon are required; calcium alginate swabs can only be used for culture and will affect the results of nucleic acid testing

(4) Pertussis culture should not use cotton swabs because they can inhibit the growth of Bacillus pertussis, but cotton swabs are not affected if only nucleic acid testing for pertussis is performed.

(5) The specimen collection site is very important to the impact of the test results, generally influenza can choose the anterior nostril area to collect nasal swabs, a little force can scrape the epithelial cells of the anterior nostril is better.

(6) Avian influenza virus receptors are mainly distributed in the lower respiratory tract, so the nasopharyngeal swab is often negative, the need to collect specimens from the lower respiratory tract as much as possible.

(7) Bacillus pertussis is mainly parasitized at the base of the nasopharynx, therefore, the collection of nasopharyngeal swabs is most suitable, while the positive rate of oropharyngeal swabs is inevitably lower than that of nasopharyngeal swabs.

Operation summary.

(1) Nasopharyngeal swab sampling needs to be preceded by nasal blowing to remove nasal secretions.

(2) The swab needs to enter vertically toward the earlobe, with the depth being the distance from the tip of the nose to the earlobe

(3) When it reaches the bottom of the nasopharynx (there is a sense of hitting the wall), it needs to stay slightly for a few seconds and then rotate and pull out

(4) Different pathogen detection requires attention to the choice of swab material and specimen collection site.