Tuberculin Skin Test (TST)
Quick Reference Guide for Health Care Providers
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Tubersol®, 1 ml syringe with 26
or 27 gauge ¼ to ½ inch needle
Alcohol swab & cotton ball
Documentation record
Anaphylaxis kit and protocol
After TST
Inject
Hold the skin taut
Position the needle bevel up,
almost flat against the skin
Insert the needle at a
5° to 15° angle until the
entire bevel is under the skin
Do not aspirate
Slowly inject Tubersol®
Use inner part of the left
forearm, 2-4 inches below
the elbow
Avoid areas with extensive
lesions, burns, eczema, rashes,
visible veins. Avoid tattoos if
possible
Use alcohol swab to clean. Do
not use topical numbing cream
Administering TST
Before TST
Prepare client
Confirm eligibility
Obtain informed consent
Tell client to:
Wait for 15 mins
after injection
Return in 48-72 hours
for test read
Prepare supplies
Tubersol®:
Protect from light.
Store between +2° to +8° C.
Use opened vials within 30 days.
Discard open vial if no date is noted.
Locate test site
Forearm &
alternate
testing sites
Load syringe
Clean top of Tubersol® vial
with alcohol swab
Do not inject air
Withdraw 0.1mL from vial
Do not preload syringes
Check
A 6-10mm diameter wheal
should form as you inject
Use a cotton ball to gently blot
any blood
Do not cover test site with
band aid
If injected too
deep, a wheal
will not form.
Advise client
Document
Mild swelling, irritation, or bruising may occur
Do not press or scratch the site
If mild itching occurs, put a cold, wet cloth on the site
Continue daily activities as normal
Follow your agency’s guidelines
(Fill TB Screening Form or equivalent)
Intradermal injection
tip: The bevel of the
needle should be
visible just below the
skin’s surface.
6-10mm wheal
If wheal does not form, or
immediately disappears, repeat
test on other forearm, or at least
2 to 4 inches below initial site.
Source: Ottawa Public Health
Bevel
July 2024
Next steps
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Use fingertips to lightly
sweep over the surface
of the forearm in a zig
zag motion
If present, find the edges
of the induration
Palpate
Tuberculin Skin Test (TST)
Quick Reference Guide for Health Care Providers
Document
Follow your agency’s guidelines (Fill TB
Screening Form or equivalent)
Record the size of induration in mm
No induration is 0 mm
Record the result as per Section 4(b)
Table 4: TST cut-off threshold points (e.g.,
positive or negative)
Note any adverse reactions
Gather supplies
Measure
Place the 0 mm on the ruler
inside the left pen marking
Measure the distance between
the pen marks in mm
Round down to the lower mm if
between ruler lines (no decimals)
Clinical decision-making
If indicated by the BCCDC TB Manual Section 4(b):
Send the client for a chest x-ray
Send the completed TB Screening Form to TB Services
Report a serious adverse reaction per your agency policy
Caliper or flexible ruler
TB Screening Form
Inspect
Visually inspect the site
under good lighting on a
firm surface
Note induration (hard,
dense, raised bump)
Mark the edges of the
induration with a pen
Do not measure redness
or soft swelling
Read across (from left to
right), not up and down
Mark edges
Reading the TST
The TST must be read
within 48 - 72 hours
of the test by a
trained health care
provider in person.
Pen method:
Move the pen tip
across the forearm
at a 45° angle
towards the test
site. The tip will
stop at the edge of
the induration. If
difficult, try holding
pen at 90°.
More Information?
Refer to the BCCDC TB Manual
Appendix A: TST Procedure
Multilingual TB client handouts:
bccdc.ca/tbresources
Do not
measure
redness
References: BCCDC TB Manual, Canadian TB Standards, CDC Mantoux TST
Facilitator Guide and CDC Mantoux Tuberculin Skin Test Wall Chart. Adapted
and reproduced with permission of Public Health, Region of Peel.
Provide the client with a copy of their result.
If indicated, explain why:
they should not have another TST in the future
they need to go for a chest x-ray
a referral to TB Services is needed
TB services may contact them for follow-up testing or
appointments (e.g. IGRA)
July 2024
Refer to BCCDC TB Manual Section 4(b) for:
TST cut-off threshold points
Special considerations for TST or IGRA testing
