Final answer:
The phlebotomy technician should use a site proximal to the IV on the non-mastectomy side.
Step-by-step explanation:
When performing a draw on an inpatient with a recent mastectomy, the phlebotomy technician should use a site proximal (close to) to the IV on the non-mastectomy side. This is because the IV running in the arm on the non-mastectomy side may affect the blood draws from the mastectomy side. Using a site proximal to the IV means choosing a site that is closer to the IV, while avoiding the arm with the IV.