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How To Swab a Throat for Testing

By

Vikas Mehta

, MD, MPH, Montefiore Medical Center

Last full review/revision Sep 2020| Content last modified Sep 2020
Click here for Patient Education
NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version

In pharyngitis (tonsillopharyngitis), testing of throat swabs may be done to identify infection with group A beta-hemolytic streptococci or N. gonorrhea.

Testing may involve traditional culture on sheep blood agar (GABHS) or Thayer-Martin medium (gonorrhea), rapid antigen testing (GABHS), or nucleic acid amplification testing (gonorrhea, COVID-19).

Indications

In patients with tonsillopharyngitis, a throat swab may need to be tested primarily to diagnose:

  • Group A beta-hemolytic streptococci (GABHS) infection

  • Gonococcal infection

Gonococcal pharyngitis may be suspected in patients with known or possible exposure to gonorrhea (eg, recent oral-genital contact).

Criteria suggestive of need for testing for GABHS pharyngitis include the presence of 2 of the following:

  • Tonsillar exudate

  • Tender lymphadenopathy

  • Fever (on examination or by history)

  • Absence of cough

Threshold for GABHS testing may be lower in patients at increased risk because of diabetes or immunocompromise.

Throat swabs are also sometimes tested if COVID-19 is suspected.

Contraindications

  • None

Complications

  • None

The swab may cause brief, minor gagging.

Equipment

  • Sterile swab

  • Tongue depressor

  • Light source; flexible lamp or head-mounted light

Use swabs supplied with the specific test kit being used or by the facility's laboratory. If none are supplied, use a swab with a plastic or wire shaft and a rayon, Dacron, or calcium alginate tip. Avoid swabs with wooden shafts and/or cotton tips because these materials may interfere with certain tests. 

Relevant Anatomy

  • The tonsils are located along the sides of the posterior oropharynx. They lie between the anterior and posterior pillars of the throat.

Positioning

  • Sitting position with head tilted back slightly

Step-by-Step Description of Procedure

  • Explain the procedure to the patient, including that they may gag briefly.

  • Wear gloves and eye protection, and if COVID-19 is under consideration, gown, N95 respirator, and face shield.

  • Position the patient and light source to illuminate the posterior oropharynx.

  • Have the patient open the mouth and relax the tongue by saying "aaaah."

  • Press the tongue down using a tongue depressor.

  • Gently rub the swab against both tonsils and the posterior pharynx.

  • Place the swab in the culture medium, transport medium, or sterile test tube.

Aftercare

  • Follow-up on test results.

Warnings and Common Errors

  • Touching the swab to the tongue or sides of the mouth

  • Not swabbing all 3 sites in the pharynx

Tips and Tricks

  • Proceed swiftly because the patient will likely gag.

  • Having the patient stick out the tongue actually stiffens it and can make it harder to see the pharynx.

Click here for Patient Education
NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version
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