There are essentially four things you have to prove. First, you have to establish the requisite standard of care. This basically means proving what the doctor was required to under the circumstances. Second, you have to prove the doctor failed to act in accordance with the standard of care. Third, you must prove that the doctors breach of the standard of care caused your injury. Fourth, you must prove the extent of your injury and the amount of damages. Fail to do any of these, and you lose your case.