19 July 2021

Accessing the nasopharynx - updated

I have no doubt that a lot of the nasopharyngeal sampling being performed around the country is collecting inadequate and potentially misleading material.

Many Most people assume that the nasal passage continues upward along the bridge of the nose.  I have cringed (and intervened) when observing even experienced medical personnel attempting to pass nasopharyngeal tubes or catheters upward (to the great discomfort of the patient).

The image embedded above is a enhanced photograph showing that access to the nasopharynx is straight back - along the roof of the mouth - NOT upward toward the brain.

The white tip of the swab in the photo is touching the nasopharynx, where Covid-19 lives.  The virus may or may not also be present in the anterior nares, and I will bet a dollar to a doughnut that lots of swabs are giving false negative results because the sinus and turbinate area is swabbed, not the nasopharynx.

A full 5-minute video (from which the screencap above was taken) is available for viewing at The New England Journal of Medicine - along with detailed information about protection for the medical worker and processing of the specimen.  Note for example the procedure for removing PPE optimally utillizes three pairs of gloves:
Remove your PPE as shown in the video and described here or in accordance with the standards at your institution. First, remove your gown and gloves. Clean your hands with an alcohol-based solution or soap and water. Put on a new [second] pair of gloves, and then remove your face shield and either dispose of it or clean and store it in accordance with the guidelines at your institution. Remove your gloves, rewash your hands, and put on another [third] pair of gloves; then remove your mask and follow your institutional guidelines for disposal or reuse. Finally, remove the last pair of gloves and wash your hands. 
Reposted from April of 2020 to add this disappointing screencap from a BBC video:

I've added a red arrow to show the direction the swab should be oriented to access the nasopharynx.  We have been living and dying with covid for more than a year, and the people whose job it is to collect vital information still are not being taught the very basics of the process.  Drives me up the wall...

Addendum - here's one more cringeworthy photo (with my annotations):

What disturbs me is not just the discomfort that these poor people are experiencing, but the possibility that the data being collected is of diminished value.  TBH, I don't know the distribution of covid in a victim or a carrier, but if like other organisms it tends to reside on the posterior nasopharyngeal wall, then these swabs of the anterior nares are going to produce false-negatives.

Addendum #2:  The comment by Eve in the Comment thread seems to indicate that anterior nasal swabs provide an adequate sample for the purposes of the CDC.  So my anxieties above may be unjustified.


  1. about two weeks before you go in for surgery, you usually have a swab like that taken to check if you have MRSA.


  2. Yes. I remember learning this first-hand (read: nose) when the doctor shoved his tonsil-grabby bite-stick horizontally into my head. I hadn't considered that a possibility until then (nor do I feel like experiencing it again anytime soon, thank you very much, what with the spot not being able to be anesthetized beforehand). Good job on the doctor knowing which way to poke though, I guess.

  3. This is the exact reason the "block head" trick works, where someone hammers a nail into their nose.

  4. I remember fondly when "a dollar to a doughnut" (or the form I typically use "dollars to doughnuts") clearly meant you were giving good odds. If you google "dunkin donuts single doughnut price" you will see that a single doughnut comes to 0.99 USD before tax.

  5. My father was an emergency room physician for a hospital in STL.
    This hospital had a contract with the city and treated prisoners of the law.
    It was a common enough event for a prisoner to feign illness and appear unconscious that my father would twirl a q-tip in the patients nose to confirm whether or not they were in fact unconscious.

    When he told me the story I tried it out on myself shortly thereafter.
    That experience alone was enough to encourage me to not put myself in a position in which the C19 test would be required.

  6. You don't seem to grasp that everything is performance now. Everyone is busking and the only evaluation is for style points. Real expertise implies knowledge, and knowledge implies the ability to understand context, and the ability to understand context implies distractibility, and distraction is an existential threat.

    1. You lost me at this point in the chain: "... the ability to understand context implies distractibility..."

  7. It hurt so badly doing the nose swab thing, that I almost preferred to have COVID-19. Now I see that it likely hurt for no good reason.

  8. That one swab test caused me sinus trouble for months.

  9. I had to have a COVID-19 test recently, and it was a self-swab. The video, illustrations, and the instructions from the nurse present had me swabbing the inside of my nostrils, not going all the way back to the nasopharynx. CDC has a PDF about it online. https://www.cdc.gov/coronavirus/2019-ncov/testing/How-To-Collect-Anterior-Nasal-Specimen-for-COVID-19.pdf

    1. Very interesting, Eve. Thank you for that link. Apparently the anterior nares may be an adequate sampling site. TBH, I'm a bit out of the loop for current practice guidelines. Perhaps I've gotten my panties into a twist for no good reason.


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