Before your doctor performs any procedure on you, he has an obligation to obtain “informed consent.” Broadly speaking, he must obtain your consent to perform the procedure, but must provide you with enough information that your consent is informed with regard to understanding the procedure itself, its purpose, its likely outcome, and – most important – the risks of the procedure.
Typical risks of surgeries, for example, include the risk of infection, blood clot and bleeding. Typical risks of anesthesia include allergic reaction, lung damage and death. Just exactly how much information should be disclosed and in what detail, is a subject of expert opinion. The doctor has a duty to be reasonable in making the disclosure, and, of course, experts may disagree over what that standard requires. If, however, a doctor does not act reasonably in providing information, then the consent is not an “informed consent,” and by proceeding without consent, the doctor is committing a tort.
If the doctor failed to obtain informed consent and the patient is injured during the procedure, the patient may have a viable malpractice claim. I say “may have” because, in order to prevail in a medical malpractice-informed consent case, the plaintiff must prove that if full disclosure had been made, the patient would not have undergone the procedure. This can be a very difficult burden, since most people who truly need medical procedures are unlikely to be deterred by a hypothetical and (usually) improbable risk. Nevertheless, if the patient can persuade a jury that he would have refused the procedure if a reasonable disclosure had been made, then the patient can prevail and be compensated for his damages. 
Interestingly, in an informed consent case, the plaintiff is not required to prove that the injurious procedure was negligently performed. According to the Supreme Court of Virginia, since the procedure would have been avoided if full disclosure had been made, there is no need to prove that the injury was the result of negligence.
About The Author: Malcolm "Mic" McConnell is a personal injury lawyer who helps injured persons get the fair compensation they deserve. He is the lead Medical Malpractice attorney at the Allen Law Firm and has nearly 30 years of experience handling cases in a variety of medical specialties. Mic was named the Best Lawyers' 2013 Medical Malpractice Law - Plantiffs "Lawyer of the Year."
 The Merriam-Webster Dictionary defines a “tort” as a “a wrongful act other than a breach of contract for which relief may be obtained in the form of damages or an injunction.” See http://www.merriam-webster.com/dictionary/tort.