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nasal_swab

nasal and nasopharyngeal swabs

see also:

Introduction

  • nasal swabs may be either:
    • “deep nasal”
      • only pass 2-3cm into the nose and are thus less “invasive”, more comfortable, less risky but for many infections are less sensitive for detecting the infection
    • “nasopharyngeal”
      • swab is directed posteriorly PARALLEL with the floor of the nasal cavity (ie. in a line directed from the nares to the external ear canal and certainly no more than 30deg upwards from this line) and as far back as to reach the nasopharynx
  • some nasal swab procedures also require the swab to be down on both sides of the nose and then, using the same swab stick to both sides of the oro-pharynx. This is routinely used in Covid-19 swabs.

Complications of swab procedure

perforation of cribriform plate and resultant CSF leak

  • the cribriform plate lies 38-52mm above the floor of the nasal cavity
  • the angle from the nares to the sphenoid opening is approximately 30deg from the horizontal floor of the nasal cavity and is reached at a distance of around 43-69mm
  • swabs inserted at 30deg or greater angle have the risk of damage to the thin and delicate areas of the skull base which form the attachment of the middle turbinate and cribriform plate which are superior and anterior to the sphenoid ostium
  • there is a risk if the patient has head extended and the operator has the swab horizonal to the ground as the floor of the nasal cavity is no longer parallel with the ground
  • perforation is generally painful at the time and within a few hours will result in unilateral CSF clear rhinorrhoea
  • this will usually require repair with a fat plus and mucosa overlay graft
nasal_swab.txt · Last modified: 2021/06/08 14:35 by gary1