When I care for a patient who's had a mastectomy, I'm always careful not to use the arm on her affected side for venipuncture or blood pressure (BP) readings. I was taught that doing so increased the risk of postmastectomy lymphedema. But some of my colleagues say it's safe to use the affected arm if the patient hasn't had any problems with lymphedema for 10 years after mastectomy. So which is it-a lifetime ban or a waiting period?-C.N., TEX.

We asked an oncology expert, who confirms that avoiding venipuncture and BP measurements on the affected arm should be a lifelong practice. Some women develop lymphedema 20 years or more after mastectomy.