What should you never do from a patient's arm who has had a mastectomy on that side?

It is essential to avoid drawing blood from the arm on the side where a patient has had a mastectomy because doing so can lead to complications. After a mastectomy, the affected side may have altered lymphatic drainage due to the removal of lymph nodes, which increases the risk of lymphedema. Lymphedema can occur when excess lymph fluid builds up in the lymphatic system, and using that arm for venipuncture can further compromise lymphatic function and exacerbate swelling.

In general, healthcare providers are trained to use the opposite arm or an alternative site for drawing blood in patients who have undergone this surgical procedure. This practice prioritizes patient safety and minimizes the risk of complications. Therefore, avoiding blood draws from the arm on the side of the mastectomy is a critical aspect of phlebotomy practice.