In Cobbs v. Grant (1972) 8 Cal.3d 229, 244-245, the California Supreme Court established a two-part test for determining a doctor's duty of disclosure to obtain a patient's informed consent to a medical procedure. "First, a physician must disclose to the patient the potential of death, serious harm, and other complications associated with a proposed procedure. (Cobbs, supra, 8 Cal.3d at p. 244.) Expert testimony on the custom of the medical community is not necessary to establish this duty. (Spann v. Irwin Memorial Blood Centers (1995) 34 Cal.App.4th 644, 656 40 Cal.Rptr.2d 360; Willard v. Hagemeister (1981) 121 Cal.App.3d 406.) Second, 'beyond the foregoing minimal disclosure, a doctor must also reveal to his patient such additional information as a skilled practitioner of good standing would provide under similar circumstances.' (Cobbs, supra, at pp. 244-245.) Therefore, expert testimony is relevant and admissible to determine the duty to disclose matters other than the risk of death or serious harm and significant potential complications. (Arato v. Avedon (1993) 5 Cal.4th 1172, 1191; Spann v. Irwin Memorial Blood Centers, supra, at p. 657, fn. 13.)" (Daum v. SpineCare Medical Group, Inc. (1997) 52 Cal.App.4th 1285, 1301-1302.) In Morgenroth v. Pacific Medical Center, Inc. (1976) 54 Cal.App.3d 521, 534-535, in affirming a grant of nonsuit, the court of appeal agreed with the trial court that expert testimony on the issue of "additional information," was required and stated, "we do not see any other rational interpretation of the above quoted language from Cobbs . . . ." (See also Betterton v. Leichtling (2002) 101 Cal.App.4th 749, 756 "Whether to disclose a significant risk is not a matter reserved for expert opinion. Whether a particular risk exists, however, may be a matter beyond the knowledge of lay witnesses, and therefore appropriate for determination based on the testimony of experts. "; Jambazian v. Borden (1994) 25 Cal.App.4th 836, 840 in affirming a grant of summary judgment, we held that to prove his informed consent claim, the plaintiff was required "to present properly qualified medical opinion evidence that his alleged diabetic condition created surgical risks other than those related by defendant prior to the procedure".) As the court in Morgenroth concluded, It stands to reason that expert testimony is necessary to establish that "a skilled practitioner of good standing would provide information on risks of the use of morphine paste in this operation under similar circumstances." (Cobbs, supra, 8 Cal.3d at pp. 244-246.)