How To Swab a Throat for Testing

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 for Swabbing a Throat

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 to Swabbing a Throa

None

Complications of Swabbing a Throat

• None

The swab may cause brief, minor gagging.

Equipment for Swabbing a Throat

• 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 for Swabbing a Throat

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

Positioning for Swabbing a Throat

Sitting position with head tilted back slightly

Step-by-Step Description of Swabbing a Throat

• Explain the procedure to the patient, including that they may gag briefly.
• Wear gloves and eye protection, and if COVID-19 (or any other airborne infection) 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 for Swabbing a Throat

Follow-up on test results.

Warnings and Common Errors for Swabbing a Throat

• Touching the swab to the tongue or sides of the mouth
• Not swabbing all 3 sites in the pharynx

Tips and Tricks for Swabbing a Throat

• 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.