How to Administer TB Tests

The TB test is an injection which can be administered by a health practitioner.

Tuberculosis (TB) is a bacterial infection. It is spread through saliva droplets emitted when an infected person coughs or sneezes. TB is a global health issue, and is potentially fatal if left untreated. The Purified Protein Derivative (PPD) TB Skin Test, also known as the Mantoux Test, was developed to test for active and latent TB. The test is carried out by a health practitioner. If your TB test result is positive, treatment for TB will follow if deemed necessary.

Things You'll Need

• Warm water
• Soap
• Towel
• Latex gloves
• Well-lit room
• Firm surface
• Alcohol wipe
• Vial of tuberculin
• Single-use disposable tuberculin syringe
• Puncture-resistant disposable container
• Cotton balls
• TB test record form
• Appointment card
• Caliper ruler

Instructions

1. Wash your hands with warm water and soap to remove any dirt or bacteria, and dry them with a towel. Put on clean latex gloves.

2. Choose a well-lit area to administer the test, and have all of the necessary equipment to hand before you begin.

3. Ask your patient to remove his jacket and roll up his sleeve to reveal his forearm. Place the patient's arm on a firm surface.

4. Ask the patient to extend his arm, with his palm facing upward and his elbow slightly flexed.

5. Select an area approximately two to four inches from the elbow toward the hand. The area must be free of tattoos, cuts, bruises and any other imperfections.

6. Clean the area using an alcohol wipe, then leave to air-dry for one minute.

7. 

   Puncture the vial with the needle, and then pull back the plunger to release the tuberculin.

   Fill the syringe with the tuberculin by puncturing the tuberculin vial with the needle at the top of the syringe. Then slowly pull the plunger at the opposite end of the syringe, withdrawing the liquid via the needle until the syringe is full.

8. Remove the needle from the empty vial and hold it upward toward the ceiling. Gentle tap the syringe with your finger to allow any air bubbles to rise to the top.

9. Push the plunger very gently to remove any air bubbles and excess tuberculin, leaving exactly 0.1 milliliter in the syringe, as indicated by the measurement on the side of the syringe.

10. Hold the syringe with your thumb and index finger as you would hold a pen, and position the syringe at a five to 15 degree angle to the patient's arm so the tuberculin will enter just below the surface of the skin.

11. Inject the tuberculin slowly. It should form a six to 10 millimeter wheal, a pale, raised area with round edges that resembles an insect bite and does not disappear immediately. Repeat the test on the opposite arm if a wheal does not appear.

12. Remove the needle and discard of it immediately in the puncture-resistant container.

13. Dab the injection area with a cotton pad if bleeding occurs, but do not apply pressure to the site or cover it with an adhesive bandage because this could cause irritation.

14. Wash your hands and record the details of the test including the location of the test (left or right arm), the tuberculin lot number and expiration date (these details are found on the tuberculin vial), date and time the test was administered and your signature.

15. Inform the patient that he must return within 48 to 72 hours to have the test result read, and make him an appointment to do so.

16. Examine the injection site upon the patient's return 48 to 72 hours later, using a caliper ruler to measure any swelling. According to the National Library of Medicine Medline Plus, an area of firm swelling greater than 15 millimeters in size indicates that the TB test is positive. For people considered at risk of contracting TB, such as those with HIV or diabetes, the amount of swelling needed to indicate a positive result is reduced to around five to 10 millimeters.

17. 

Tips & Warnings

• Discard the tuberculin vial if it has passed its expiration date or the seal is broken, and use a new vial.

• The results of the TB test will vary among ages and people with certain health problems, so it is advisable to get the patient's medical history.

• Ask your patient if they are taking any medication; drugs like steroids could affect the accuracy of the test result.

• A positive skin test does not necessarily mean that the patient has active TB, it might be latent, so further tests will be needed to determine this.

• Advise the patient to keep the injection site clean and dry and free from lotions and adhesive bandages.

• According to the National Library of Medicine's Medline Plus, the test isn't 100 percent accurate, and up to 20 percent of people with TB produce a negative result when given the TB test.

• This test should be administered by an experienced health professional only.

• Patients who have had a positive TB test result in the past should not be given the test again.

• Mild itching, swelling and redness is common after the test and normally clears up within seven days.

References

• NHS Choices: Tuberculosis
• National Library of Medicine & National Institute of Health: Medline Plus: PPD Skin Test
• Public Health Grey Bruce Health Unit: Tuberculosis Skin Test- Mantoux

Resources

• Centre for Disease Control and Prevention: Tuberculin Skin Testing
• Mayo Clinic: Tuberculosis Test and Diagnosis