Poor technique of COVID-19 swab test can be life-threatening, study finds

By Melissa Coade

May 3, 2021

Nasal swab RT-PCR testing is often used as the main diagnostic test method.
Nasal swab RT-PCR testing is often used as the main diagnostic test method. (Image: Adobe/Paul Maguire)

If you’ve been watching news footage of the invasive nose and throat swabbing involved in some COVID-19 tests with a grimace, good news from Finland suggests that the risk of injury from the procedure is ‘extremely low’ but excessive force during the procedure can cause harm.

Finnish researchers have demonstrated that there is an ‘extremely low’ risk of injury from the COVID-19 swab test and determined that the procedure known as ‘nasopharyngeal sampling’ is safe. 

In a seven-month observational study of more than 600,000 Finnish citizens in a Helinski catchment area who were tested for COVID-19, only eight people were taken to the emergency department due to a mishap in the swabbing process. 

Of that group, four people required a broken swab to be removed from their nasal passages and the other half presented with nose bleeds that required ‘serious medical attention’ — two people presented to hospital with a potentially life-threatening condition. None of the patients returned positive COVID-19 test results.

“The broken swabs were removed via nasal endoscopy under local anesthesia, whereas the nasal bleeds required medication, numerous nasal packings, and surgical and endovascular procedures and led to fetal risk, sepsis, and blood transfusions,” the study said.

In the rare case (1.24 per 100,000 people) where a patient is taken to the emergency department due to a mishap during their nasal swab procedure, the study flagged excessive use of force or ‘an overly cranial direction of the swab’ as the main risk factors.

Researchers from the University of Helsinki set out to investigate the frequency and type of COVID-19 nasopharyngeal test complications, recognising that timely and reliable testing was an important public health measure to control the pandemic. As a testing method, the researchers said nasal and throat swabbing was one of the best.

“Nasopharyngeal swab RT-PCR testing is often used as the main diagnostic test method because it yields early results with moderate sensitivity and excellent specificity,” the paper said. 

But the researchers were also cognisant that swabbing of the nasal passage is intrusive to a part of the human anatomy adjacent to other vital structures such as the orbit and skull base. 

“Sampling should always be performed bearing in mind the anatomical structures of the nasal cavity and its surroundings to ensure safe sampling and correct results,” the researchers said.

“Force should never be used, especially in patients with known prior operations of the nose or skull base. The sampling swab should be directed along the nasal floor, not too laterally nor too cranially, until resistance is encountered.”

“Complications involve anatomically challenging locations and may be life threatening. To avoid complications, correct sampling techniques are crucial,” they added.

The study was published in the journal JAMA Otolaryngology-Head & Neck Surgery on Friday.


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