At what angle should a needle be inserted for performing a venipuncture?

In performing a venipuncture, the needle should typically be inserted at an angle of 15-30 degrees. This angle is optimal for accessing the vein without causing excessive trauma to the vessel. At this angle, the needle is introduced just above the vein, which allows it to slide smoothly into the lumen of the vein while minimizing discomfort for the patient.

Using this angle also helps in easily locating the lumen of the vein and reduces the risk of hitting the back wall or going through the vein altogether. Additionally, it provides a stable trajectory for blood flow into the collection device and enables better visualization and confirmation of vein entry.

The other angles provided in the question may lead to either difficulty in accessing the vein or potential injury to surrounding tissues; for instance, angles above 30 degrees can increase discomfort and the likelihood of complications, while angles significantly lower than 15 degrees may not properly penetrate the vein, making it challenging to secure a blood sample.