It is important to select the appropriate needle for the situation. A needle that is too large may damage a vein needlessly, and a needle that is too small may hemolyze the specimen.

• Needle color codes vary among manufacturers; however, several large manufacturers use yellow for 20-gauge, green for 21-gauge, black for 22-gauge needles, and blue for 23-gauge.

method of blood collection

• syringe system

• ETS

• butterfly (winged infusion set)