FAQs
What makes a syringe a "tuberculin" syringe?
A tuberculin syringe is a 1 mL syringe with very fine graduations, typically in hundredths of a milliliter, designed to measure the small doses used in tuberculin skin testing. Its precision also makes it useful for other small-volume injections, such as some vaccines, allergen doses, and pediatric medications.
Is 27G x 1/2" right for a tuberculin skin test?
Tuberculin skin tests are given intradermally, just under the skin surface, so they require a short, fine needle. A 27-gauge, 1/2" needle is a common choice for this. Follow current CDC guidance and your facility's protocol on technique, angle, and reading the result. Read results within the window your protocol sets.
Can a TB syringe be used to give insulin?
No. TB syringes are graduated in milliliters, while insulin syringes are marked in insulin units for a specific concentration. Using a TB syringe for insulin invites conversion errors and dangerous dosing mistakes. Always use an insulin syringe that matches the insulin concentration being given. Keep TB and insulin syringes in separate bins.
Why does a fixed needle help with low dead space?
A detachable needle has a hub that sits on the syringe tip, and fluid collects in that connection. With a permanently fixed needle, there is no separate hub, so less medication is left behind after the plunger is fully depressed. That is one reason TB syringes often use fixed needles.
How do I read a 0.1 mL dose accurately?
Hold the syringe at eye level, expel any air bubbles, and align the plunger stopper's leading edge (the edge closest to the needle) with the 0.1 mL mark. Fine graduations make this easier on a 1 mL barrel, but take a second look before injecting. A second check catches most errors.
