Plastic surgery is only covered if it is medically necessary. If it is entirely elective, then it will most likely not be covered.
Surgeries that should be covered are plastic surgery after an accident or a cleft palate or plastic surgery in conjunction with necessary surgery. Medically needed surgeries, such as a deviated septum should be covered, while a nose job for cosmetic purposes would not be.
Items such as breast implants, liposuction, rhinoplasty, etc are not covered. Breast implants would be covered if they are done after a mastectomy, however.Breast reduction, on the other hand, would most likely be covered is it is done to ease discomfort.
Consult your insurance agent. Many companies offer different plans.