Final answer:
The hematoma in the given scenario is caused by the needle being at too shallow of an angle, resulting in slow blood flow.
Step-by-step explanation:
The cause of the hematoma in the given scenario is that the needle was at too shallow of an angle. When performing a venipuncture, it is important for the phlebotomy technician to insert the needle at the correct angle to ensure proper blood flow and minimize complications. In this case, the 15° angle is not sufficient to penetrate the vein properly, leading to slow blood flow and the formation of a hematoma.
Learn more about Venipuncture complications