delivered the opinion of the Court. Davidson, J. dissents and filed a dissenting opinion at page 239 infra.
The parties in this appeal, Katie Sue Sard and her husband, David Penn Sard, Jr., appellants, and Erving D. Hardy, M.D., appellee, went to trial before a jury and Judge • Harry E. Clark, Jr. in the Circuit Court for Talbot County, on an amended declaration containing eight causes of action asserted by Mrs. and Mr. Sard against Dr. Hardy.
Suit was filed on 29 August 1972. The amended declaration was filed on 1 February 1973. Trial was held on 26 and 27 March 1974. At the close of all of the evidence offered by the plaintiffs, the defendant filed a motion for a directed verdict. Maryland Rule 552. After hearing arguments, the court granted the motion. On 1 April 1974 the plaintiffs filed a motion for a new trial. That motion was heard by Judge Clark on 28 July 1975, and was overruled. Judgment absolute was entered. The plaintiffs appealed.
We shall discuss briefly the significant allegations *219of the amended declaration, to aid in understanding the legal foundations upon which the several claims rest.
The first three causes of action are asserted only by Mrs. Sard. In the first she said that Dr. Hardy was a licensed physician, a specialist in obstetrics and gynecology, and in the performance of bilateral tubal ligation to prevent pregnancy; that in March 1968 she employed Dr. Hardy to treat her for the purpose of accomplishing sterilization; that she had undergone several difficult prior pregnancies, terminating in Caesarean sections, and Dr. Hardy recommended that she be sterilized; that on 26 March 1968 Dr. Hardy delivered her child by Caesarean section and attempted to perform a bilateral tubal ligation upon her, and represented to her that it would accomplish sterilization. She alleged that Dr. Hardy did not use the usual, ordinary, or accepted method of performing that operation or, in the alternative, that he was so negligent in performing the operation as to fail totally in accompplishing its purpose; and that in April 1970 she again became pregnant. The other allegations related primarily to damages.
In her second cause of action Mrs. Sard adopted the allegations of the first, except as to negligent performance of the operation, and alleged that Dr. Hardy negligently failed to inform her that the surgical procedure for sterilization was not absolute, and that the possibility did exist that she could thereafter become pregnant, so that she might declare her decision in accepting or rejecting the procedure.
The third cause of action differed only in that the negligence alleged was that Dr. Hardy advised her after the delivery and operation that she could engage in sexual intercourse with safety and could not become pregnant, and that he gave this advice without having performed suitable postoperative tests to ascertain the success or failure of the operation.
The fourth, fifth, and sixth causes of action, asserted by both plaintiffs, paralleled the first, second, and third, respectively, and differed only in that they claimed damages incurred jointly by both plaintiffs.
*220The seventh cause of action, by Mrs. Sard alone, alleged that Dr. Hardy expressly warranted the success of the operation. The eighth, brought by both plaintiffs, was based upon the same allegation of express warranty, and claimed joint damages.
Mrs. Sard’s relevant medical history as disclosed by the record was that in December 1965, when she was eight months pregnant, she developed eclampsia and severe convulsions. An emergency Caesarean section was performed. The baby did not survive. She first saw Dr. Hardy, the defendant in this case, in October 1966, after she had become pregnant a second time. He rendered routine prenatal care, and on 4 March 1967 delivered a normal baby girl by Caesarean section in the hospital at Easton. There were no complications.
Dr. Hardy again saw Mrs. Sard when she came to him on 28 November 1967. She was five months pregnant. He rendered care through an uneventful prenatal course, culminating in the delivery of a normal baby girl on 26 March 1968 by Caesarean section, at The Memorial Hospital at Easton. At the same time Dr. Hardy performed upon Mrs. Sard an operative procedure described as a bilateral tubal ligation.
In June 1970 Mrs. Sard, suspecting that she was pregnant, consulted a different physician, who confirmed that she was. The time of conception was estimated to have been the middle of April 1970, slightly more than two years after the tubal ligation was performed. The child was born at the hospital in Cambridge in January 1971.
At the trial of the case Mr. and Mrs. Sard relied upon the testimony of four witnesses to support the issues of liability. The witnesses were Dr. Hardy, called by the plaintiffs as an adverse witness, Mr. Sard, Mrs. Sard, and Dr. Eldon L. Hawbaker, who had been in training as a resident in general surgery in the hospital in March 1968, and had assisted Dr. Hardy at the operation. Dr. Hawbaker was called by the defendant out of turn, by agreement, to testify that he had dictated the operative report, and that it was true, to the best of his knowledge. The record suggests that during cross *221examination, the plaintiffs made him their witness for a limited purpose.
The issues, as they were pleaded and tried below, fell into four areas, which we summarize as follows:
1. That the doctor was negligent in the manner in which he performed the sterilization operation. (First and fourth causes of action.)
2. That the doctor was negligent in failing to inform his patient of facts material to her consent to the sterilization operation. (Second and fifth causes of action.)
3. That the doctor was negligent in failing to perform postoperative tests to ascertain the success or failure of the operation. (Third and sixth causes of action.)
4. That the doctor expressly warranted to his patient that the operation would accomplish sterilization. (Seventh and eighth causes of action.)
In argument to Judge Clark on the motion for a directed verdict, plaintiffs’ counsel relied for evidence of negligent performance upon the eventual “failure” of the operation — recanalization of a fallopian tube. The trial judge rejected that argument, and granted the motion as to the first and fourth causes of action. The issue is not raised or argued in this appeal.
As to the alleged failure to make postoperative tests for success or failure, plaintiffs’ counsel conceded below that there was no evidence to support that claim, and that the motion should be granted as to the third and sixth causes of action. It was. The issue is not raised or argued in this appeal.
Two issues are raised in this appeal as to the correctness of the directed verdict, and an error in ruling on evidence is asserted.
In their brief, appellants state the Questions Presented in this way:
I. Was it error for the trial court to direct a *222verdict in favor of the Defendant, Dr. Ervin D. Hardy?
A. Was the plaintiffs evidence legally sufficient to sustain a finding by the jury that Dr. Hardy had failed to obtain an informed consent from Mr. and Mrs. Sard prior to the sterilization of Mrs. Sard?
II. Was it error for the trial court to refuse to allow Dr. Hawbaker, who had assisted Dr. Hardy in Mrs. Sard’s sterilization, to testify as to the standard of care required of physicians and surgeons who performed sterilizations in Easton, Maryland in 1968.
III. Was it error for the trial court to hold that Dr. Hardy’s express warranty of sterilization was unenforceable for lack of consideration.
Consent to Operate
Generally, a physician has no right to operate upon the body of a patient without that patient’s consent.1 To do so has been treated historically by the courts as a battery, or assault and battery. As the Court of Appeals of New York, through Cardozo, J. said in Schloendorff v. Society of New York Hospital, 211 N. Y. 125, 105 N. E. 92 (1914):
“Every human being of adult years and sound mind has a right' to determine what shall be done with his own body; and a surgeon who performs an operation without his patient’s consent commits an assault, for which he is liable in damages.”
In that case the testimony of the patient was that she had consented to an abdominal operation for the purpose of examination, but had notified the doctor that there must be no operation. The surgeon who operated removed a tumor. The Court held that the hospital was not liable for the *223physician’s wrong, but said of it, “ * * * the wrong complained of is not merely negligence. It is trespass.”
The assault and battery theory has been widely applied, with some of the cases holding that an apparent consent which is not “informed” is no consent at all. In A. Holder, Medical Malpractice Law, 228-29 (1975), the author explains:
“There are two different legal theories to support actions by plaintiffs alleging lack of consent. The original theory on which this cause of action was predicated was that treatment to which the patient had not knowingly consented was a classic example of the tort of ‘assault and battery.’ This is still the case where the patient is in total ignorance of what is to be done.”
“The other approach to this problem is to treat it as negligence and allege that a physician’s failure to explain the consequences of treatment to which the patient has consented without understanding is negligence per se and a violation of the requisite standards of due care. In most cases in which the doctrine of informed consent arises, the patient is aware of the nature of the procedure which he is to undergo and has in fact signed a consent for it. What he does not understand is that there are some risks of permanent damage inherent in the procedure. Failure to have told him this means that the action is one in negligence.
“The practical difference between the two theories is that if assault and battery is alleged, no expert testimony is required to prove it. Lay witnesses are sufficient. On the other hand, in most, but not all, states, before a claim of medical negligence can go to the jury for determination, expert testimony to the fact that the reasonably careful physician would have explained the given risk is required.”
*224An interesting observation of the change in the trend of judicial thinking is found in W. Prosser, The Law of Torts 165-66 (4th ed. 1971), which says:
“A considerable number of late cases have involved the doctrine of ‘informed consent,’ which concerns the duty of the physician or surgeon to inform the patient of the risk which may be involved in treatment or surgery. The earliest cases treated this as a matter of vitiating the consent, so that there was liability for battery. Beginning with a decision in Kansas in 1960, it began to be recognized that this was really a matter of the standard of professional conduct, since there will be some patients to whom disclosure may be undesirable or even dangerous for success of the treatment or the patient’s own welfare; and that what should be done is a matter for professional judgment in the light of the applicable medical standards. Accordingly, the prevailing view now is that the action, regardless of its form, is in reality one for negligence in failing to conform to the proper standard, to be determined on the basis of expert testimony as to what disclosure should be made. The factors to be considered by the physician or surgeon include the likelihood and seriousness of the bad result, the feasibility of alternative methods, the interest of the patient, knowledge of his past history, his emotional stability, the necessity of treatment, and the existence of an emergency.”
Perhaps the most articulate and exhaustive judicial discussion of the “informed consent” principle is found in the case of Cobbs v. Grant, 8 Cal. 3d 229, 104 Cal. Rptr. 505, 502 P. 2d 1 (1972), written by Justice Mosk for the Supreme Court of California. The case had been submitted to a jury on a claim that the physician was negligent in undertaking and in performing an operation for a duodenal ulcer, and on a claim that the physician’s failure to disclose the inherent *225risks of the initial surgery vitiated the patient’s consent to operate.
The patient’s course following the surgery was complicated by three occurrences. He suffered internal bleeding which required an emergency operation for the removal of his spleen, because an artery at the hilum of the spleen had been severed during the operation. This was stated to be a risk inherent in the type of surgery performed. A month or two later the patient developed pains, which were caused by a developing gastric ulcer. The evolution of a new ulcer was stated to be another risk inherent in the surgery performed. A third operation, removal of one half of the patient’s stomach, was performed to relieve the gastric ulcer. Still another hospitalization was required because of internal bleeding due to the premature absorption of a suture, another inherent risk. This condition abated without further surgery.
The California court held that there was not substantial evidence to support a jury verdict on the issue of liability for negligence in deciding to operate, or in performing the surgery, and reversed the judgment against the physician, for retrial. The court then discussed the question of informed consent. We shall quote portions of that discussion, generally omitting the numerous citations it contains. Justice Mosk wrote:
“Where a doctor obtains consent of the patient to perform one type of treatment and subsequently performs a substantially different treatment for which consent was not obtained, there is a clear case of battery.
“However, when an undisclosed potential complication results, the occurrence of which was not an integral part of the treatment procedure but merely a known risk, the courts are divided on the issue of whether this should be deemed to be a battery or negligence.
*226“Although this is a close question, either prong of which is supportable by authority, the trend appears to be towards categorizing failure to obtain informed consent as negligence. That this result now appears with growing frequency is of more than academic interest; it reflects an appreciation of the several significant consequences of favoring negligence over a battery theory. As will be discussed infra, most jurisdictions have permitted a doctor in an informed consent action to interpose a defense that the disclosure he omitted to make was not required within his medical community. However, expert opinion as to community standard is not required in a battery count, in which the patient must merely prove failure to give informed consent and a mere touching absent consent.
“We agree with the majority trend. The battery theory should be reserved for those circumstances when a doctor performs an operation to which the patient has not consented. When the patient gives permission to perform one type of treatment and the doctor performs another, the requisite element . of deliberate intent to deviate from the consent given is present. However, when the patient consents to certain treatment and the doctor performs that treatment but an undisclosed inherent complication with a low probability occurs, no intentional deviation from the consent given appears; rather, the doctor in obtaining consent may have failed to meet his due care duty to disclose pertinent information. In that situation the action should be pleaded in negligence.
“The facts of this case constitute a classic illustration of an action that sounds in negligence. Defendant performed the identical operation to which plaintiff had consented. The spleen injury, development of the gastric ulcer, gastrectomy and internal bleeding as a result of the premature *227absorption of a suture, were all links in a chain of low probability events inherent in the initial operation.
“Defendant * * * points out that the majority of the California cases have measured the duty to disclose not in terms of an absolute, but as a duty to reveal such information as would be disclosed by a doctor in good standing within the medical community. * * * Moreover, with one state and one federal exception every jurisdiction that has considered this question has adopted the community standard as the applicable test. Defendant’s second contention is that this near unanimity reflects strong policy reasons for vesting in the medical community the unquestioned discretion to determine if the withholding of information by a doctor from his patient is justified at the time the patient weighs the risks of the treatment against the risks of refusing treatment.
“Despite what defendant characterizes as the prevailing rule, it has never been unequivocally adopted by an authoritative source. Therefore we probe anew into the rationale which purportedly justifies, in accordance with medical rather than legal standards, the withholding of information from a patient. /
“Preliminarily we employ Several postulates. The first is that patients aril generally persons unlearned in the medical sciences and therefore, except in rare cases, courts may safely assume the knowledge of patient and physician are not in parity. The second is that a person of adult years and in sound mind has the right, in the exercise of control over his own body, to determine whether or not to submit to lawful medical treatment. The third is that the patient’s consent to treatment, to *228be effective, must be an informed consent. And the fourth is that the patient, being unlearned in medical sciences, has an abject dependence upon and trust in his physician for the information upon which he relies during the decisional process, thus raising an obligation in the physician that transcends arms-length transactions.
“From the foregoing axiomatic ingredients emerges a necessity, and a resultant requirement, for divulgence by the physician to his patient of all information relevant to a meaningful decisional process. In many instances, to the physician, whose training and experience enable a self-satisfying evaluation, the particular treatment which should be undertaken may seem evident, but it is the prerogative of the patient, not the physician, to determine for himself the direction in which he believes his interests lie. To enable the patient to chart his course knowledgeably, reasonable familiarity with the therapeutic alternatives and their hazards becomes essential.
“Therefore, we hold, as an integral part of the physician’s overall obligation to the patient there is a duty of reasonable disclosure of the available choices with respect to proposed therapy and of the dangers inherently and potentially involved in each.
“A medical doctor, being the expert, appreciates the risks inherent in the procedure he is prescribing, the risks of a decision not to undergo the treatment, and the probability of a successful outcome of the treatment. But once this information has been disclosed, that aspect of the doctor’s expert function has been performed. The weighing of these risks against the individual subjective fears and hopes of the patient is not an expert skill. Such evaluation and decision is a nonmedical judgment reserved to the patient alone.
*229“The scope of the disclosure required of physicians defies simple definition. Some courts have spoken of ‘full disclosure’ * * * and others refer to ‘full and complete’ disclosure, * * * but such facile expressions obscure common practicalities. Two qualifications to a requirement of ‘full disclosure’ need little explication. First, the patient’s interest in information does not extend to a lengthy polysyllabic discourse on all possible complications. A mini-course in medical science is not required; the patient is concerned with the risk of death or bodily harm, and problems of recuperation. Second, there is no physician’s duty to discuss the relatively minor risks inherent in common procedures, when it is common knowledge that such risks inherent in the procedure are of very low incidence.
“In sum, the patient’s right of self-decision is the measure of the physician’s duty to reveal. That right can be effectively exercised only if the patient possesses adequate information to enable an intelligent choice. The scope of the physician’s communications to the patient, then, must be measured by the patient’s need, and that need is whatever information is material to the decision. Thus the test for determining whether a potential peril must be divulged is its materiality to the patient’s decision.
“We point out, for guidance on retrial, an additional problem which suggests itself. There must be a causal relationship between the physician’s failure to inform and the injury to the plaintiff. Such causal connection arises only if it is established that had revelation been made consent to treatment would not have been given. Here the record discloses no testimony that had plaintiff *230been informed of the risks of surgery he would not have consented to the operation.
“The patient-plaintiff may testify on this subject but the issue extends beyond his credibility. Since at the time of trial the uncommunicated hazard has materialized, it would be surprising if the patient-plaintiff did not claim that had he been informed of the dangers he would have declined treatment. Subjectively he may believe so, with the 20/20 vision of hindsight, but we doubt that justice will be served by placing the physician in jeopardy of the patient’s bitterness and disillusionment. Thus an objective test is preferable: i.e., what would a prudent person in the patient’s position have decided if adequately informed of all significant perils.”
What the California court said in Cobbs v. Grant, supra, closely parallels much of what was said by Robinson, J. for the court in Canterbury v. Spence, 464 F. 2d 772 (D.C. Cir. 1972). In addition, however, it includes what we feel is a more illuminating discussion of whether the scope of the duty of disclosure is measured by lay standards or by medical standards. On this question there is a substantial division of authority.2
Although it seems to be the fact, as appellants stat¿ in their brief, that there is no Maryland authority ruling on *231informed consent, the principle was applied in Kruszewski v. Holz, 265 Md. 434, 290 A. 2d 534 (1972), apparently by common acquiescence of both parties, the trial court, and the Court of Appeals. One of the patient’s allegations was that the doctor was negligent in failing to inform her adequately of the possible risks of and alternatives to the operation. Expert opinion evidence was received on the question of whether the standard of care required of a physician was satisfied when he merely informed his patient that a hysterectomy was major surgery and complications could arise. Questions presented to and decided by the Court of Appeals involved the proper wording of hypothetical questions, and the adequacy of a special issue submitted to the jury to present the question of whether the doctor deviated from the standard of care by not sufficiently informing the patient of the alternatives and risks involved in obtaining her consent to operate. The very existence, in the law of Maryland, of a duty to disclose, and the extent of such a duty, were not before the Court.
Upon our consideration of the leading recent cases and the texts, we embrace the principle of informed consent, and we hold that it should be applied by the courts of Maryland in appropriate cases where there is a claim of professional negligence in failing to meet a duty to disclose.
The duty is to make an adequate disclosure of substantial facts which would be material to the patient’s decision. The trial court must decide as a matter of law, on the facts and circumstances of each case, whether the evidence is sufficient to support a finding by the jury that there has been a negligent failure to disclose such facts.
A subsidiary question, which also must be decided by the trial court as a matter of law, on the facts of each case, is whether the duty to disclose is to be determined by standards of the profession, thus requiring expert opinion evidence,3 or may be determined by a jury without the aid of *232expert opinion. We do not agree that either rule could be applied in all cases.
We now examine the evidence in the case before us, so that we may determine whether there was any evidence tending to show a negligent failure by Dr. Hardy to disclose to Mrs. Sard any substantial fact which would have been material to her decision.
It is perfectly clear that Mrs. Sard consented to the performance upon her by Dr. Hardy of the surgical procedure medically described as bilateral tubal ligation — she so alleges in her declaration. She said that they discussed the fact that she did not want to have any more children, and he suggested birth control pills, an intrauterine device, or sterilization. She rejected the first two choices. He told her that he could sterilize her by tying her tubes, at the time of the Caesarean section delivery. As she put it, “I thought sterilize meant fix you so you can’t have no more kids, so I took it.” The doctor did not discuss with her the technique he was going to use to tie her tubes, or advise her that there were different methods of sterilization.
It is equally clear that the tubal ligation was to be performed at the same time as the delivery. A month or a couple of weeks before delivery Dr. Hardy had told her to go home and think about it, and let him know. She did, and told him, “I would rather be sterilized.”
It is also clear that Mr. Sard was in no way involved in any of the discussions between Mrs. Sard and Dr. Hardy. Mr. Sard testified that the first time he ever saw Dr. Hardy to speak to was in June 1970, when he told Dr. Hardy that Mrs. Sard was pregnant again.
There was very little evidence concerning risks or hazards inherent in the sterilization operation recommended by Dr. Hardy. It seems logical that they would add little, if anything, to the risks and hazards inherent in the delivery of a child by Caesarean section. Whatever those added risks *233and hazards might have been, they were successfully avoided by Dr. Hardy, or by Providence, or both. None developed. To repeat what we quoted above from Cobbs v. Grant, supra:
“Two qualifications to a requirement of ‘full disclosure’ need little explication. First, the patient’s interest in information does not extend to a lengthy polysyllabic discourse on all possible complications. A mini-course in medical science is not required; the patient is concerned with the risk of death or bodily harm, and problems of recuperation. Second, there is no physician’s duty to discuss the relatively minor risks inherent in common procedures, when it is common knowledge that such risks inherent in the procedure are of very low incidence.”
There was no evidence that Mrs. Sard suffered any ill effects from the sterilization procedure, during her recuperation or at any later time. It would be safe to say that at no time did any physical manifestation make her aware that the tubal ligation had been performed.
Appellants do not complain that the performance of the tubal ligation brought any harm upon Mrs. Sard. They do not complain that the operation should not have been performed. They do not contend on appeal that the ultimate failure resulted from negligence by Dr. Hardy. Their sole complaint, stated narrowly but accurately, is that the operation failed to provide,' permanently, the expected benefit.
That any medical or surgical therapy or procedure may fail to accomplish the desired, or even the reliably expected result, seems to be universally recognized, both in medicine and in law. That recognition is inherent in the statement for the Court of Appeals by Chief Judge Brune in Lane v. Calvert, 215 Md. 457, 138 A. 2d 902 (1958), at 462-63:
“It is well established by the case law in this State that the mere fact that an unsuccessful result *234follows medical treatment is not of itself evidence of negligence.”
It is reflected also in that Court’s consistent rejection of the rationale of res ipsa loquitur in medical malpractice cases. Lane v. Calvert, supra; Johns Hopkins Hospital v. Genda, 255 Md. 616, 258 A. 2d 595 (1969), and cases cited therein.
The absence of negligence in spite of an unfavorable result is not in all circumstances the equivalent to the absence of negligence in failure to disclose risks and hazards to the patient. In an excellent discussion of informed consent the Supreme Court of Rhode Island said in Wilkinson v. Vesey, 295 A. 2d 676 (R.I. 1972):
“Having established defendants’ duty to disclose, we will now delineate the extent of the disclosure which should be made. Obviously there is no need to disclose risks that are likely to be known by the average patient or that are in fact known to the patient usually because of a past experience with the procedure in question. * * * It is not necessary that a physician tell the patient any and all of the possible risks and dangers of a proposed procedure. * * * As we noted earlier, materiality is to be the guide. It is our belief that, in due deference to the patient’s right to self determination, a physician is bound to disclose all the known material risks peculiar to the proposed procedure. Materiality may be said to be the significance a reasonable person, in what the physician knows or should know is his patient’s position, would attach to the disclosed risk or risks in deciding whether to submit or not to submit to surgery or treatment.” 295 A. 2d 689.
The evidence in this case shows that the physical harm to the patient was zero; that there was one chance in fifty 4 *235that the benefit would be zero, and forty-nine chances in fifty that the benefit would be all that the patient desired.
On that evidence we hold that a reasonable person, in Mrs. Sard’s position, would attach no material significance to the risk of one chance in fifty that she would derive no benefit from the operation. It is significant, and by itself perhaps fatal to her claim, that she produced no evidence to show that she would have refused the operation if she had known 5 that there was a chance of failure.
Although the trial judge did not arrive at his ruling by *236quite the same route that we have followed, he reached the correct result when he granted a directed verdict on the second and fifth causes of action, based upon the allegation that Dr. Hardy was negligent in failing to inform Mrs. Sard adequately before obtaining her consent.
Ruling on Evidence
We have set out the questions presented in appellants’ brief. One of them asks if the court erred in refusing to allow Dr. Hawbaker to testify as to a standard of care. The short answer is that the witness simply was not asked to give such an opinion.
The court had asked the witness if he felt qualified to give an expert opinion, and the witness had said, “No, sir. Absolutely not.” True, the question was couched in terms of “this hospital community”, but the witness was not asked a question which might have been proper under Shilkret v. Annapolis Emergency Hosp., supra.
We see no erroneous ruling.
Express Warranty
Allegations contained in the seventh and eighth causes of action asserted by Mrs. and Mr. Sard leave some doubt as to the warranty claimed. One allegation states that Dr. Hardy “expressly warranted” that the tubal ligation “would accomplish sterilization”, while a later allegation refers to his “warranty” that the “the operation was a complete success”.
The first suggests an expected future result. The other suggests a result already accomplished. Although it is possible to make either or both of such warranties, there is a significant difference between them. The principal difference is that an alleged warranty of a past fact has no legal validity unless it is supported by an independent consideration.
In the record in this case there is no evidence of a pre-operative warranty. Dr. Hardy’s suggestion to Mrs. Sard that she be sterilized by tying her tubes cannot be construed as an express warranty of result.
*237Appellants rely for support of the alleged warranty upon statements which they say Dr. Hardy made to them after the operation had been performed. We quote from Mrs. Sard’s direct examination:
“Q. When the Doctor said that he would sterilize you, what, in fact, what was his conversation to you about?
A. All he said was sterilize me so I thought sterilize meant fix you so you can’t have no more kids, so I took it.
Q. Did the Doctor ever tell you you couldn’t have any more kids after he sterilized you?
A. Yes, he did.
Q. What did he tell you?
A. On the day he let me go home from the hospital he told me before I walked out the door, ‘Go home. Have all the fun you want. You don’t have to worry about getting pregnant’.
Q. Before you went to the hospital did the Doctor inform you you would not have to worry about getting pregnant if you were sterilized?
A. After I was sterilized he did.”
“Q. Now after you had the sterilization did you again, after a period of time, resume some type of sexual activity with your husband?
A. Yes.
Q. Did you take any precautions to prevent child birth?
A. No.
Q. Why not?
A. Because Dr. Hardy told me I was sterile and would not have to worry about getting pregnant, a guaranteed operation.”
*238Mr. Sard was asked about his contact with Dr. Hardy in June, 1970. The transcript shows:
“A. I went to Dr. Hardy’s office.
Q. Why did you go to Dr. Hardy’s office then?
A. I figured he was the one that fixed her. I wanted to know whether she could get pregnant or not.
Q. Had you been to his office before that?
A. No, sir.
Q. What was your temperament, how did you feel?
A. I don’t know, I just wanted to find out if she could get pregnant or not.
Q. What did the doctor say to you when you went to his office?
A. I went down there and Dr. Hardy and his nurse, and we went in the back room and I asked Dr. Hardy about it and he said, ‘It ain’t no way she can be pregnant. It’s a guaranteed operation. Don’t worry about it. Go ahead on home’.”
Dr. Hardy’s version of what he told Mrs. Sard when she left the hospital was, “I told her that I had tied her tubes and she should be sterile. She didn’t have to worry * * * about becoming pregnant.”
If these statements, viewed most favorably to the appellants, could be considered as more than ordinary medical reassurance, and could be construed as an express warranty, the warranty lacked consideration, and was invalid.
The requirement that such a contract by a physician be supported by consideration is discussed in Annotation, Contract to Effect Specific Medical Result, 43 A.L.R. 3d 1221, in which it is stated, at 1233:
“No case herein denies that the general rule of contract law that any contract must be supported by consideration to be enforceable is applicable to a *239physician’s contract to effect a cure or specific result. In the following cases, moreover, the courts have stated that such a contract would not be supported by the consideration paid for the physician’s normal undertaking to use due care and skill, but under the particular circumstances involved, must be supported by a separate consideration.”
Cases which hold that an asserted express warranty by a physician, made after the agreement to operate had been reached, must be supported by a separate consideration, are Herrera v. Roessing, 533 P. 2d 60 (Colo. App. 1975); Coleman v. Garrison, 349 A. 2d 8 (Del. Supr. 1975); Rogala v. Silva, 305 N.E.2d 571 (Ill. App. 1973); Gault v. Sideman, 191 N.E.2d 436 (Ill. App. 1963); and Wilson v. Blair, 211 P. 289 (Mont. 1922).
The Annotation suggests that in cases which have not required a showing of a separate consideration, the alleged warranties were made before the agreement for the physician’s services was reached.
We consider it logical, and consistent with other legal principles, to hold that an alleged express warranty cannot be enforced as a warranty unless, (1) it was made before the operation was performed, and was relied upon by the patient in contracting for the service, or, (2) it was supported by a separate consideration. We do so hold.
There was no evidence in this case of a separate consideration for the alleged express warranty made after the operation. Therefore, there was no enforceable warranty. The directed verdict on the seventh and eighth causes of action was correct.
Judgment affirmed.
Appellants to pay costs.
. We are not dealing here with an emergency which requires prompt action, or with consent given by one person on behalf of another who is, at the time, incapable of making a decision.
. Some of the cases which have held that expert opinion evidence of the standard of care is required are Getchell v. Mansfield, 489 P. 2d 953 (Ore. 1971); Ohligschlager v. Proctor Community Hosp., 283 N.E.2d 86 (Ill. 1972); Trogun v. Fruchtman, 207 N.W.2d 297 (Wis. 1973); Downer v. Veilleux, 322 A. 2d 82 (Me. 1974); and Young v. Group Health Cooperative, 534 P. 2d 1349 (Wash. 1975).
Contrary holdings are found in Canterbury v. Spence, supra; Wilkinson v. Vesey, 295 A. 2d 676 (R.I. 1972); Congrove v. Holmes, 308 N.E.2d 765 (Ohio 1973); and Scaria v. St. Paul Fire and Marine Ins. Co., 227 N.W.2d 647 (Wis. 1975).
See also, Annotation, Necessity and Sufficiency of Expert Evidence to Establish Existence and Extent of Physician’s Duty to Inform Patient of Risks of Proposed Treatment, 52 A.L.R. 3d 1084, and Harney, Medical Malpractice (1973) at 63.
. When the standard of care rendered by other physicians is an issue, many of the cases and writers say that the evidence must relate to the same community, or locality. Maryland takes a broader view. In Shilkret v. Annapolis Emergency Hosp., 276 Md. 187, 349 A. 2d 245 (1975), the Court of Appeals held, without regard to a geographical medical community or *232locality, that, “a physician is under a duty to use that degree of care and skill which is expected of a reasonably competent practitioner in the same class to which he belongs, acting in the same or similar circumstances.” Id. at 200.
. It was brought out in the plaintiffs’ examination of Dr. Hardy that the technique he chose to employ in the tubal litigation at the time of a Caesarean section had, according to a study on the subject, a failure rate of one in fifty.
. The parties, and the trial judge, placed more importance than we do upon an authorization form, signed by Mrs. Sard and Mr. Sard before the operation. It was requested of them by the hospital, not by Dr. Hardy. It said:
“A UTH ORIZA TION FOR STERILIZATION
Date 3-25-68
I/We do hereby request and authorize the Memorial Hospital and the doctors thereof to perform upon Mrs. Katie Sue Sard , an operation intended to effectuate sterilization.
I/We understand what is meant by sterilization and I/We understand that if this operation is successful, the above named patient will be unable in the future to produce children, but I/We understand that an operation intended to effect sterilization is not effective in all cases. I/We consider that this operation will be for the best interest and physical well being of the above named patient. I/We have come to the hospital voluntarily and I/We hereby certify that the above named patient is submitting voluntarily to the operation.
Being mentally capable of giving a valid authorization I/We are signing this paper of our own free will and accord.
David P. Sard, Jr. Katie Sue Sard”
Spouse Patient
Two individuals, presumably hospital personnel, signed as witnesses.
Mr. Sard testified that he signed the authorization, but did not read it. He said that he could not read. He finished the eighth grade in school. He did not ask anyone to read it t<5 him, or to explain it to him.
Mrs. Sard testified that the form was presented to her 10 or 15 minutes before she was taken to the operating room. She was told that it was necessary, to authorize the sterilization. She said that she did not read it, nor ask for any further explanation. She was not in any pain, and did not remember that she had any medication.
We do not discuss the general rule of law that a person is bound by what he signs, whether he reads it or not. The significance of the authorization is the statement that an operation intended to effect sterilization is not effective in all cases. We have already concluded in this case that the risk of failure was not material to the patient’s decision.