Nurses and other Medical Professions in the US and Europe are prohibited from having tattoos. Health organizations have rules that say if a nurse was to have a tattoo should not be visible. The organization says that a nurse should not have body piercing or other ornaments on her body.
I have seen nurses with tattoos. With that being said, you may not win hospital administration over if you plan on working at Mt. Sinai Medical Center sporting Aryan Nations ink, especially if it is visible. Just saying.