What gauge needle is most commonly used for routine venipuncture?

The most commonly used gauge needle for routine venipuncture is a 21-gauge needle. This size strikes a balance between providing adequate flow and minimizing tissue trauma, making it an ideal choice for drawing blood in various patient populations. The 21-gauge needle is thick enough to efficiently allow a smooth and swift withdrawal of blood, which is crucial for laboratory testing, while still being small enough to reduce discomfort during the procedure.

Using a larger needle, such as an 18-gauge, might be appropriate for specific situations where a larger volume of blood is needed rapidly, but it can also cause more pain and bruising for patients. Smaller gauge needles, like the 25-gauge and 30-gauge, are typically used for more delicate tasks such as drawing blood from infants or for specific procedures that require less blood volume. However, they may lead to slower blood flow and higher chances of hemolysis, making them unsuitable for routine venipuncture in the majority of adult patients.