Final answer:
Palpating a vein helps determine the size, depth, and direction of the vein, which are important characteristics for venipuncture.
Step-by-step explanation:
The purpose of palpating a vein is to determine all of the following characteristics of a suitable vein for venipuncture: size, depth, and direction. Palpating a vein allows the healthcare professional to assess the blood pressure within the vein, blood flow within the vein, and the return of blood to the heart. By feeling the size, depth, and direction of a vein, a healthcare professional can choose the most suitable vein for venipuncture.