An alternative way to perform diagnostic nasopharyngeal swab for SARS-CoV-2 infection

Abstract

On March 11, 2020, WHO has defined the novel coronavirus disease SARS-CoV-2 (COVID-19) outbreak as a pandemic and still today continues to affect much of the world. Among the reasons for the rapid spread of SARS–CoV-2 infection, there is not only the high transmissibility of the virus, but also the role of asymptomatic or minimally symptomatic carriers. Therefore diagnostic testing is central to contain the global pandemic. Up to now real-time reverse transcriptase polymerase chain reaction (RT-PCR)–based molecular assays for detecting SARSCoV-2 in respiratory specimens is the current reference standard for COVID-19 diagnosis. Nasopharyngeal swab is the preferred choice for SARS–CoV-2 testing; however is not always a free of complications procedure. In patients with severe coagulopathies or diseases such as HHT, the risk of nosebleeding may be high. As in all those conditions like advanced stage sinonasal neoplasms or unfavorable anatomical characteristics, the nasopharyngeal swab may not be feasible.

This work reports a safe and effective procedure of nasopharyngeal swab collection for COVID-19 testing, through the transoral way, in patients with contraindication to perform it transnasally.

The procedure proved feasible and well tolerated. The discomfort for the patient is comparable with the execution of an oropharyngeal swab without exposing him to additional complications.

In selected cases, the procedure described represents a valid alternative to nasopharyngeal swab performed transnasally. In particular, it allows reaching the area with the highest diagnostic sensitivity. Moreover it can be performed by Otolaryngology and, with adequate training, also by non-specialist staff.

1. Introduction

On Jan. 30, 2020, WHO has declared that the outbreak of 2019-nCoV constituted a Public Health Emergency of International Concern (PHEIC), whereas on March 11, 2020, declared the novel coronavirus disease SARS-CoV-2 (COVID-19) outbreak as a pandemic. The pandemic of coronavirus disease continues to affect much of the world, and as of Nov.03, 2020 globally, there have been 46.403,652 confirmed cases of COVID-19, including 1.198,569 deaths [1].

In response to COVID-19, countries across the globe have implemented a range of public health and social measures, like partial or total closure of public places, quarantine, national and international travel restrictions.

Among the reasons for the rapid spread of SARS–CoV-2 infection, there is not only the high transmissibility of the virus, but also the role of asymptomatic or minimally symptomatic carriers. Particularly, COVID-19 seems to be transmitted mostly during the incubation period, when most of patients have very mild non-specific symptoms. Therefore diagnostic testing, to identify people infected with COVID-19, is central to contain the global pandemic [3]. The development of diagnostic tests has been rapidly progressing and up to now real-time reverse transcriptase polymerase chain reaction (RT-PCR)–based molecular assays for detecting SARS– CoV-2 in respiratory specimens are the current reference standard for COVID-19 diagnosis [2].

Based on current knowledge regarding the sensitivity of the molecular test, the highest positive detection rate is from lower respiratory tract specimens [2]. However, especially in asymptomatic or paucisymptomatic patients, collection of these specimens is not easily feasible; alternatively it is possible to perform a nasopharyngeal or oropharyngeal swab, among which, the nasopharyngeal one has a higher sensitivity [3].

Nasopharyngeal specimen is the preferred choice for swab-based SARS–CoV-2 testing because, in addition to having greater sensitivity, is considered rapid and safe [4]. However it is not always a procedure simple and free of complications. In patients with severe coagulopathies or diseases such as HHT, the risk of nosebleeding may be high. As in all those conditions like advanced stage sinonasal neoplasms or unfavorable anatomical characteristics, the nasopharyngeal swab may not be feasible.

Supporting Video demonstrates a safe and effective procedure of nasopharyngeal swab collection for COVID-19 testing, through the transoral way, in patients with contraindication to performe it transnasally.

2. Methods

As recommended by WHO guidelines, it is important to wear appropriate personal protective equipment (PPE) included gloves, surgical face masks, protective goggles, face shields and gowns, as well as specific procedures- filtering facepiece respirators (e.g. N95 or FFP2 or FFP3 standard or equivalent) [4].

Before starting, to improve the success of the procedure it is important that the patient is adequately informed, inviting him to relax, breathe slowly from the mouth to reduce pharyngeal reflexes and stiffening.

To perform the test use a plastic swab with the possibility of being folded manually. The stick of the swab is manually modified at a distance of approximately 3.5 cm from the sampling end, with an angle of about 80° (Fig. 1 ).

Fig. 1.

Modified oropharyngeal swab.

The plastic stick of the swab is manually modified at distance of approximately 3.5 cm from the sampling end, with an angle roughly 80°.

It is advisable the use of tongue depressor for better exposure, especially in case of unfavorable oral cavity morphology, like macroglossia, palatine tonsillar hypertrophy or Mallampati type III - IV. In poorly compliant patients it is possible to precede the procedure by administering local anesthesia using Lidocaine spray, having previously investigated any allergies. It is also recommended the use of the front light, in order to have a better control of the procedure.

The operator asks the patient to open the oral cavity as much as possible. While inserting the swab, avoid contact with oral cavity structures in particular with the tongue. Reached the oropharynx at level of the uvula, orient the collecting end of the swab upwards, and then gently swing the swab in latero-lateral and/or cranio-caudal sense for a few seconds. To be sure of reaching the nasopharynx, the angled segment of the swab must be fully beyond the soft palate (Fig. 2 ).

Fig. 2.

Procedure of nasopharyngeal swab for COVID-19 diagnosis through the transoral way.

(A) Transoral view: the swab reaches the oropharynx at level of the uvula with the collecting end oriented upwards. (B) Transoral view: to be sure of reaching the nasopharynx, the angled segment of the swab must be fully beyond the soft palate.

(C) Transnasal view: the swab is in nasopharynx it is rotated in a latero-lateral and/or cranio-caudal sense for a few seconds.

At the end of the procedure, the swab must be inserted into the test tube taking care not to contaminate adjacent surfaces and medical staff. Although the shape of the swab has been modified, its structure is malleable and can be adapted again to the rigid test tube (Fig. 3 ).

Fig. 3.

Specimen handling.

At the end of the procedure the swab must be inserted into the test tube. Although the shape of the swab has been modified, its structure is malleable and can be adapted again to the rigid test tube.

3. Results

The procedure proved feasible and well tolerated. The use of tongue depressor and Lidocaine spray improve the success of the procedure, especially in those poorly compliant patients in whom pharyngeal reflexes are easily triggered. The discomfort for the patient is comparable with the execution of an oropharyngeal swab without exposing him to additional complications. The plastic swab is readily available and the folding maneuver is easily obtained.

4. Discussion

Diagnostic tests to identify people infected with COVID-19 are critical to adopt the adequate medical and epidemiological measures necessary to control the global pandemic [3]. In particular a quick identification of cases among hospitalized patients remains a high priority to prevent nosocomial spread with subsequent occurrence of outbreaks [2].

The primary, and preferred, method for diagnosis is the collection of upper respiratory samples via nasopharyngeal swabs, which, compared to the oropharyngeal swab, has a greater sensitivity [3].

In fact nasopharyngeal swabs showed higher positive rate than oropharyngeal swabs for SARS-CoV-2 detection, and oropharyngeal swabs may result in a worryingly high false negative rate [3]. The high number of false negatives depends also on inappropriate timing of collection and inadequate sampling technique or specimen handling [5].

To minimize the rate of false negatives, the execution of the nasopharyngeal swab must be preceded by adequate training of health professionals. However, even experienced operators in performing the procedure in patients with a higher risk of epistaxis, with anatomical anomalies or nasal pathologies that contraindicate the execution may present difficulties.

The procedure described, in selected cases, represents a valid alternative to nasopharyngeal swab performed transnasally. In particular, it allows reaching the area with the highest diagnostic sensitivity, when the nasopharyngeal specimen is not possible to obtain or is contraindicated. Furthermore, it is not necessary to have special equipment, except a moldable swab.

With adequate training the transoral nasopharyngeal swab can be performed by non-specialist staff. However the otolaryngologist who is more familiar with head-neck surgical maneuvers and has greater knowledge of the pharyngeal anatomy, guarantees best comfort for the patient, shorter execution time and greater chance of success.

Voice over transcription

00:00–00:12: This is a demonstration of a nasopharyngeal swab for diagnosis of SARS-CoV-2 infection performed transorally, using an 80 degree angled swab.

00:13–00:51: On March 11, 2020, World Health Organization has defined the novel coronavirus disease SARS-CoV-2 (COVID-19) outbreak as a pandemic and still today continues to affect much of the world.

Among the reasons for the rapid spread of SARS–CoV-2 infection, there is not only the high transmissibility of the virus, but also the role of asymptomatic carriers.

Therefore diagnostic testing, to identify people infected with COVID-19, is central to contain the global pandemic [3].

00:52–01:47: Up to now real-time reverse transcriptase polymerase chain reaction (RT-PCR) - based molecular assays for detecting SARS– CoV-2 in respiratory specimens are the current reference standard for COVID-19 diagnosis [2].

Based on current knowledge, the highest positive detection rate is from lower respiratory tract specimens [2].

Alternatively, especially in asymptomatic or paucisymptomatic patients, it is possible to perform a nasopharyngeal or oropharyngeal swab, among which, the nasopharyngeal one has a higher sensitivity [3].

Nasopharyngeal specimen is the preferred choice for swab-based SARS–CoV-2 testing because, in addition to having greater sensitivity, is considered rapid and safe [4].

01:48–02:17: However it is not always a procedure simple and free of complications.

In patients with severe coagulopathies or diseases such as Hereditary Hemorrhagic Teleangiectasia, the risk of nosebleeding may be high. As in all those conditions like advanced stage sinonasal neoplasms or unfavorable anatomical characteristics, the nasopharyngeal swab may not be feasible.

02:18–02:33: The aim of this study is to demonstrate a safe and effective procedure of nasopharyngeal swab collection for COVID-19 testing, through the transoral way, in patients with contraindication to perform it transnasally.

02:34–04:27: As recommended by WHO guidelines, it is mandatory to wear appropriate personal protective equipment (PPE) [4].

To perform the test use a plastic swab with the possibility of being folded manually. The stick of the swab is manually modified at a distance of approximately 3.5 cm from the sampling end, with an angle of about 80°.

Before starting, to improve the success of the procedure it is important that the patient is adequately informed, inviting him to breathe slowly from the mouth to reduce pharyngeal reflexes and stiffening. In poorly compliant patients it is possible to precede the procedure by administering local anesthesia using Lidocaine spray. It is advisable the use of tongue depressor for better exposure, especially in case of unfavorable oral cavity morphology, like macroglossia or Mallampati type III and IV. It is also recommended the use of the front light, in order to have a better control of the procedure.

The operator asks the patient to open the oral cavity as much as possible.

While inserting the swab, avoid contact with oral cavity structures in particular with the tongue. Reached the oropharynx at level of the uvula, orient the collecting end of the swab upwards, and then gently swing the swab in latero-lateral and/or cranio-caudal sense for a few seconds.

At the end of the procedure, although the shape of the swab has been modified, its structure is malleable and can be adapted again to the rigid test tube.

04:28–04:58: The procedure described, in selected cases, represents a valid alternative to nasopharyngeal swab performed transnasally. In particular, it allows reaching the area with the highest diagnostic sensitivity, when the nasopharyngeal specimen is not possible to obtain or is contraindicated. Furthermore, it is not necessary to have special equipment, except a moldable swab.

04:59–05:16: The procedure proved feasible and well tolerated. The discomfort for the patient is comparable with the execution of an oropharyngeal swab without exposing him to additional complications.

05:17–05:45: With adequate training the transoral nasopharyngeal swab can be performed by non-specialist staff. However the otolaryngologist who is more familiar with head-neck surgical maneuvers and has greater knowledge of the pharyngeal anatomy, guarantees best comfort for the patient, shorter execution time and greater chance of success.

The following is the supplementary data related to this article.

Supporting Video demonstrates a safe and effective procedure of nasopharyngeal swab collection for COVID-19 testing, through the transoral way, in patients with contraindication to perform it transnasally.

Financial material & support

None.

Declaration of competing interest

The authors disclose no conflicts of interest.