(a) A health care provider is liable for failure to obtain the informed consent of a patient if the claimant establishes by a preponderance of the evidence that the provider has failed to inform the patient of the common risks and reasonable alternatives to the proposed treatment or procedure, and that but for that failure the claimant would not have consented to the proposed treatment or procedure.
(b) It is a defense to any action for medical malpractice based upon an alleged failure to obtain informed consent that
(1) the risk not disclosed is too commonly known or is too remote to require disclosure;
(2) the patient stated to the health care provider that the patient would undergo the treatment or procedure regardless of the risk involved or that the patient did not want to be informed of the matters to which the patient would be entitled to be informed;
(3) under the circumstances consent by or on behalf of the patient was not possible; or
(4) the health care provider after considering all of the attendant facts and circumstances used reasonable discretion as to the manner and extent that the alternatives or risks were disclosed to the patient because the health care provider reasonably believed that a full disclosure would have a substantially adverse effect on the patient's condition.