Action by plaintiffs Oscar A. Fehrman (hereinafter Fehrman) and Gretta Fehrman, his wife, against defendant Dr. Warren G. Smirl for damages arising from injury to Fehrman alleged to have resulted from the medical malpractice of defendant.

The complaint among other things alleged that on September 29, 1958, defendant performed an operation on Fehrman known as a suprapubic prostatectomy (removal of prostate gland); that defendant, during the course of this operation and of his subsequent treatment of Fehrman, failed to use and exercise that degree of skill, care, and judgment which is to be expected of, and is required of, the ordinarily prudent and qualified surgeons in the city of Waukesha; and that as a result of defendant's negligence, Fehrman has suffered permanent urinary incontinence (inability to control one's urine) and sexual impotence. Defendant's answer denied the allegations of the complaint with respect to negligence and alleged as an affirmative defense that, upon information and belief, syphilis of the central nervous system together with incompetent treatment thereof had contributed to Fehrman's impotence and urinary incontinence following surgery.

The action was tried in February, 1962, to a court and jury. The ensuing statement of facts constitutes a summary of much of the material testimony and evidence adduced at the trial.

At the time defendant operated upon him on September 29, 1958, Fehrman was fifty-three years of age and a plasterer by occupation who had resided in Waukesha for about nine years. At the time of trial, Dr. Smirl was forty-one years of age so at the time of the operation he was either thirty-seven or thirty-eight. He is a duly licensed physician and surgeon. Dr. Smirl received his bachelor's degree from Carroll College and his M. D. degree from Columbia University's School of Medicine in 1945. He had internships in hospitals in Milwaukee and San Antonio, Texas, where he received training in surgery. Thereafter, he served in a hospital in Wilmington, Delaware, as a resident surgeon and in the United States Air Force for three and one-half years during which time he practiced medicine but not operative surgery. He then came to Waukesha where he has been engaged in the general practice of medicine and surgery for some years. He also has taken short courses in surgery in Vienna, Austria, and in Chicago at Cook County Hospital. He is a member of the active surgical staff of Waukesha Memorial Hospital.

Fehrman had experienced difficulty in voiding urine for some months prior to September, 1958, which caused him to get up several times each night. The testimony is in dispute as to whether Fehrman had noticed this difficulty for nine months or two years. Nevertheless, early in September, 1958, Fehrman consulted Dr. Smirl, whom he had never met before, with respect to this urinary difficulty. Dr. Smirl conducted a residual urine test on Fehrman on two occasions at his office by having him expel the urine from his bladder and then inserting a catheter or rubber tube in his urinary canal to remove any additional urine. Normally one would be able to expel all but an ounce or two of urine but in Fehrman's case he left behind 260 cubic centimeters on two occasions. Dr. Smirl also conducted a rectal examination by which he felt the prostate and found it soft and compressible without any evidence of hard or stony nodules. He diagnosed the complaint as benign enlarged prostatic hypertrophy. Dr. Smirl thereupon advised Fehrman that he would have to undergo surgery for the removal of his prostate gland.

On September 26, 1958, Fehrman entered Waukesha Memorial Hospital. Three days later, Dr. Smirl performed the operation, known as a suprapubic prostatectomy, assisted by Drs. Davies and Sydow, both of whom testified at the trial. Dr. Smirl made a vertical cut in Fehrman's abdominal wall and bladder wall large enough to admit his fist. The walnut-sized, doughnut-shaped prostate gland lay near the bladder neck about one and one-half inches from the external sphincter just as a small doughnut might lie in a funnel with the flared portion of the funnel being equivalent to the bladder as it tapers toward the bladder neck, and the spout being equivalent to the urinary canal, or prostatic urethra. This sphincter is a ring of muscle which by contracting and expanding acts as a valve in controlling the flow of urine from the bladder through the prostatic urethra. The operation consisted of shelling the prostate from its bed with the index finger of the surgeon. Bleeding in the raw bed was controlled by pressure of hot compresses applied by the surgeon. Thereafter, two catheters, or rubber tubes, were inserted, one, through the urinary canal, terminated in a Bardex bag, which was pulled down over the raw bed for six hours before being released (because tension for a longer time could injure the external sphincter) so as to control bleeding; and the other through the abdominal opening which was then sutured. Dr. Smirl's report of the operation noted that the abdominal cut had inadvertently been extended just behind the pubic bone which made the suturing of the incision somewhat more difficult.

After the operation, drainage was to continue through the two catheters leading from the bladder to collecting bags. The upper catheter carried most of the drainage; very little drainage came from the catheter in the urinary canal. Dr. Smirl attempted to get the lower catheter draining by directing frequent irrigations of the urinary canal with a warm saline solution so as to open up the apparent blockage and to prevent any blood clots from filling up the bladder and clogging the urinary canal. When the lower catheter refused to drain despite these measures, Dr. Smirl called in Dr. McDonell, a specialist in urology — apparently with Fehrman's consent. Dr. McDonell attempted to change the catheter in the urinary canal on several occasions in hopes of getting better drainage.

Fehrman was anxious to return home and the doctors apparently felt that he could do so despite the absence of satisfactory recovery at that point from the operation. He was released from the hospital on October 18, 1958. Thereafter, Dr. Smirl visited him at home on several occasions and continued to irrigate the lower catheter which still did not drain properly. During this time plaintiff's urine was draining through the upper catheter and also out through the abdominal opening, which had not yet healed, causing both his clothes and his bedding to become wet. During one home visit on October 29th, Dr. Smirl was unable to replace a catheter which he had removed, and he decided to take plaintiff back to the hospital.

After Dr. McDonell had similarly failed to insert the catheter at the hospital, Drs. Smirl and McDonell took Fehrman to the operating room where the abdominal cut was opened by Dr. McDonell. He found a dense ring of scar tissue in the bladder neck, opened up the obstruction, which had prevented drainage from the lower catheter, by use of his finger, and inserted the catheter. The lower catheter drained properly after this operation. Fehrman stayed in the hospital about ten days and was discharged from the hospital on November 8, 1958. At this time Dr. Smirl suggested that Fehrman continue to consult with Dr. McDonell who was treating plaintiff with a "sound" or narrow, curved rod which was inserted in the urinary canal to dilate the bladder neck so as to prevent obstruction at the point at which the earlier obstruction had been located.

About two weeks after Fehrman went home, the abdominal cut healed and drainage no longer came from that point. Nevertheless, during this time Fehrman apparently was not wearing a catheter and thus his clothes were wet most of the time because he was unable to hold his urine.

In May of 1959, Fehrman went to the Mayo Clinic at Rochester, Minnesota, in an attempt to improve his situation. The findings of the clinic were sent to Dr. Smirl although he denied receiving one letter which made reference to a central nervous system syphilitic condition. Fehrman was told of this condition while at the clinic.

Fehrman first consulted Dr. Axel Trangsrud of Milwaukee, a specialist in urology, about December 1, 1959, at which time he was admitted to a Milwaukee hospital for further tests. These tests revealed the central nervous system syphilitic condition which, however, Dr. Trangsrud did not begin to treat with penicillin until the following July. Dr. Trangsrud used an instrument called a cystoscope in examining Fehrman. This instrument has a metal tube with a lens at its tip which is illuminated by artificial light. It is inserted up the urinary canal and into the bladder and functions something like a periscope. By its use the physician can see the prostatic urethra wall and the interior of the bladder. There is a dispute in the testimony as to whether a physician can also see the external sphincter and its functioning.

Dr. Trangsrud's findings, after the hospital tests had been completed, were that Fehrman's sphincter was damaged and that its elastic quality was absent. In describing what he found by use of the cystoscope, Dr. Trangsrud stated, "I found a portion of the sphincter, which I found moving and trying to close the flow of urine, as I removed the cystoscope, it should properly be called a remnant." (The trial court instructed the jury to disregard this last-quoted testimony for a reason hereinafter explained in the opinion.) Dr. Trangsrud stated that the loss of function of the sphincter valve "could not have come from anything else except the surgery and the manipulation procedures that followed it." Dr. Trangsrud also found a stricture just above the sphincter "being a scar-tissue formation partially obstructing and occluding the outflow of urine, that was independent and separate from the sphincter changes."

Dr. Trangsrud treated Fehrman up to the time of trial by inserting metal sounds in his urinary canal about twice a month to relieve the stricture. As a result of this treatment he testified there is no longer a problem or condition of excessive tissue and bladder-neck contracture, and that neither scar tissue nor contracture now interferes with the functioning of the sphincter. Dr. Trangsrud further testified to a reasonable medical certainty that damage to the sphincter was responsible for its nonfunction and that this condition would be permanent.

Defendant Smirl testified in his own behalf. The other medical witnesses whom he called were Drs. Timothy McDonell, Gwilym Davies, Herbert Sydow, and John W. Kearns. In addition, the deposition of Dr. G. J. Thompson was read into the record. Drs. McDonell, Kearns, and Thompson are specialists in urology. McDonell practices at Waukesha, Kearns at Milwaukee, and Thompson has been head of the urology department of the Mayo Clinic since 1939. Drs. Davies and Sydow are physicians and surgeons practicing at Waukesha. They are familiar with the suprapubic prostatectomy operation and have performed this operation although they are not specialists in urology.

Both Drs. Smirl and McDonell attributed the nonfunctioning of the external sphincter to the formation of scar tissue in the prostatic urethra in the vicinity of the sphincter. They testified that this scar tissue made the urethra rigid so that the contracting sphincter muscle could not close the urethra. As Dr. McDonell explained, it would be like putting a rubber band around a stovepipe.

Dr. Smirl testified that in performing the suprapubic prostatectomy, it is important to keep one's finger in the capsule in which the prostate gland is located because "if you get your finger out of the capsule, you damage the external sphincter." He further stated, "I was very careful to keep the finger inside the prostatic capsule so when I did pull the prostate gland, I wasn't tugging on the external sphincter, that can damage it too." In another place in his testimony Dr. Smirl was asked these questions and gave these answers:

" Q. Now, you do not know to a certainty, do you, that the external sphincter was uninjured as a result of your surgery? A. It could have been a result of the surgery.

" Q. This you could not see? A. You can't see it.

" Q. Visually? A. No."

Dr. McDonell testified that in performing a suprapubic prostatectomy, the removal of the prostate by use of the finger is like removing the orange and leaving the peel. It was his opinion that both the scarred prostatic urethra and the bladder-neck contracture were beyond the surgeon's control. He further stated, "I do not see how one can tear the sphincter in a suprapubic prostatectomy in all honesty," and, "I am not sure it can be damaged with the finger no more than a rubber band can."

Dr. Davies testified that he assisted Dr. Smirl in performing the suprapubic prostatectomy on Fehrman and was familiar with the manner in which this type of operation is performed by general practitioners who practice in the Waukesha area. He had performed about 40 or 50 of these operations himself, and had observed about the same number performed by others. He stated that it was his opinion to a reasonable medical certainty that Dr. Smirl performed this operation on Fehrman with that degree of skill and care which other doctors of the same school of medicine usually exercise in Waukesha county.

Dr. Sydow acted as the anesthetist when Dr. Smirl operated on Fehrman. Sydow has practiced medicine and surgery at Waukesha since 1930 and has performed one or two suprapubic prostatectomies each year during such period. He was asked whether he had an opinion to a reasonable medical probability whether or not, in the operation and treatment of Fehrman, Dr. Smirl exercised the professional skill and judgment normally exercised by physicians of the same school of medicine in the Waukesha area. He replied that he did have such opinion which was that, "I think the entire procedure was well done."

Dr. Kearns testified as follows: When a man has an obstructed bladder neck due to an enlarged prostate for a long time, his problem is trying to get the urine through rather than holding it in. The sphincter muscle is not as functional as when he was younger, nor is he accustomed, in view of the obstruction, to keeping it shut. Most men, after undergoing a prostatectomy, can regain complete tone again, but some cannot regain tone again although they have excellent sphincters which can be demonstrated with a cystoscope. Incontinence can occur after removal of the prostate gland without any injury to the sphincter. Nevertheless, a suprapubic prostatectomy in a man of Fehrman's age "is very much on the young side." Some patients react to scarring differently than others. The scar contracts as the healing progresses. Some people overcontract. The method followed by Dr. Smirl in performing the operation was the standard method of performing this operation. In the course of a suprapubic prostatectomy, the surgeon must be careful in enucleating (or removing) the prostate gland to avoid damage to the sphincter.

In his deposition Dr. Thompson testified as follows: At the time Fehrman was at the Mayo Clinic, two staff members examined him and then a consultation was held with Dr. Thompson. The external sphincter is at least an inch and a half from the outlet of the bladder. The area between the bladder and sphincter is known as the prostatic urethra. The cystoscopic examination by these other two staff members "showed marked cicatricial deformity [scarring] of the prostatic urethra and region of the external sphincter apparently some of the latter has been removed by the previous surgical procedure." The verumontanum, which is a structure located between the bladder neck and sphincter where the ejaculatory ducts, which carry seminal fluid, empty into the urethra, was absent. This absence indicated "that in the course of operation this area was adherent to the tissue which was enucleated, and it didn't separate in an ordinary or normal way." The scarring of the prostatic urethra in the region of the sphincter "can explain incontinence." He has seen patients who have suffered incontinence for longer intervals than has Fehrman and yet have finally regained full control. Bladder-neck contracture is a recognized complication in prostatic surgery, and is not usually due to negligence on the part of the surgeon. Dr. Smirl's method of conducting the operation, as described in a hypothetical question, is the acceptable and standard method of performing such operation.

The expert medical testimony established that the syphilis of Fehrman's central nervous system was not a cause of his incontinence although it might have caused his impotency. Nevertheless, Fehrman offered no expert medical testimony to support the allegation of the complaint that the impotency was caused by any act of Dr. Smirl. Thus by the time the action went to the jury, any issue having to do with syphilis or impotency had virtually disappeared.

A special verdict was submitted and returned by the jury as follows:

"Question One: Did the defendant, Dr. Warren Go Smirl, fail to use that degree of care and skill which surgeons in good standing of the same school of medicine who practice in the city of Waukesha or vicinity usually exercise with respect to the operation and postoperative care of the plaintiff, Oscar A. Fehrman?

"Answer: No.

"Question Two: If you answer Question One `Yes,' then answer this question: Was the failure to use the degree of care required, so found by you in answering Question One, a cause of the disability of Oscar A. Fehrman with respect to the operation and postoperative care?

"Answer: _____.

"Question Three: Irrespective of your answers to the previous question, you will answer this question: What sum of money will reasonably compensate the plaintiff, Oscar A. Fehrman, for the damages and disability sustained by him as a natural result of the operation and postoperative care with respect to:

"(a) Pain and suffering, past and future? Answer: $5,000.

"(b) Loss of wages, past and future? Answer: $35,700.

"(c) Permanent disability? Answer: $3,000.

"(d) Future medical expense? Answer: $5,000.

"Question Four: Irrespective of your answers to the previous questions, you will answer this question: What sum of money will reasonably compensate the plaintiff, Gretta Fehrman, for the damages, if any, sustained by her as a natural result of the disability of Oscar A. Fehrman with respect to:

"(a) Loss of society and companionship? Answer: $3,000."

Judgment was entered upon the verdict on April 13, 1962, dismissing the complaint upon the merits with costs Plaintiffs Fehrman have appealed therefrom.

CURRIE, J.

Plaintiffs Fehrman first contend that the trial court erred in not changing the answer to Question One of the verdict from "No" to "Yes," and in then not answering the unanswered causation question "Yes," so as to entitle plaintiffs to judgment on the special verdict for the damages found by the jury. Should they not prevail with respect to this contention, they then request a new trial be cause the trial court erred: (1) In its rulings on evidence, (2) in certain instructions included in the charge to the jury, and (3) in refusing to give an instruction grounded on res ipsa loquitur. In addition to resolving these issues raised by plaintiffs, we have also considered whether this court should exercise its discretion under sec. 251.09, Stats., and grant a new trial in the interest of justice.

Causal Malpractice as a Matter of Law.

In order for this court to find that the trial court erred, in not changing the answer to Question One of the special verdict from "No" to "Yes" and in not answering the causation question "Yes," we would have to find Dr. Smirl chargeable with malpractice as a matter of law and find that such malpractice caused Fehrman's disability. This we cannot do upon the evidence presented by the record on this appeal. Since plaintiffs have contended that they are entitled to judgment as a matter of law, we have recounted at considerable length, in the preceding statement of facts, a comprehensive synopsis of the evidence which we deem material on this issue. This synopsis of the evidence discloses two theories, advanced by the expert medical testimony, as explanations of the permanent urinary incontinence which Fehrman has sustained.

The first of these conflicting theories, upon which plaintiffs rely, is based upon the testimony of Dr. Trangsrud. This theory holds that the external sphincter was injured either in the performance of the original operation by Dr. Smirl or in the postoperative care given by Drs. Smirl and McDonell for which Dr. Smirl would be liable.

The opposing theory, advanced by Drs. Smirl and McDonell, is that scar tissue formed in the prostatic urethra in the vicinity of the external sphincter, without fault on Dr. Smirl's part, and resulted in such rigidity that the sphincter cannot function. Plaintiffs attack this testimony on two grounds. First, they assert that Drs. Smirl and McDonell were interested rather than unbiased witnesses. Nevertheless, this was a factor to be considered by the jury in passing on their credibility as witnesses. This court cannot deem their testimony so incredible as to afford no support for the jury's answer to the first question of the verdict. Second, plaintiffs point to Dr. Trangsrud's testimony that, by reason of his course of treatment after Fehrman left the care of Drs. Smirl and McDonell, the scarred-tissue condition of the prostatic urethra had been cleared up so that a normal sphincter would now be able to function. Plaintiffs contend that this testimony of Dr. Trangsrud must be accepted as a verity. We are disinclined to so hold, however, because it falls within the field of expert testimony which the jury has the option to accept or disregard.

The lack of direct eyewitness testimony that the sphincter was injured during the course of the original operation or postoperative care presents a serious flaw in plaintiffs' theory. Expert, medical-opinion testimony must be relied upon to prove this, but even then the jury is not bound to accept such testimony. Furthermore, there is no direct expert, medical testimony that, if the sphincter was so injured during such time, it could only have occurred through the negligence of Drs. Smirl or McDonell. There is expert medical testimony which will support this inference, but again the jury is not bound to draw such an inference.

The first question of the verdict clearly presented an issue of fact for the jury, and the trial court would have erred had it changed the jury's answer thereto.

Rulings on Evidence

In the course of the cross-examination of Dr. Kearns, plaintiffs' counsel asked this question, "And is it not also a fact that the sphincter may be damaged by enucleation where it is either fibrous or adhesive and difficult to remove where it is proximate to the sphincter?" An objection was interposed to the question "as assuming something which was not present in this case," and the trial court sustained the objection. Prior to this ruling Dr. Trangsrud had testified that he had found that Fehrman's external sphincter had been damaged, that in his opinion the damage to the sphincter was responsible for its present failure to function, and that in his opinion the damage to the sphincter had resulted from the operation and the related manipulations that followed it. Dr. Thompson's deposition had also been read into the record previously. In this deposition Dr. Thompson had stated that the verumontanum, which lies between the bladder neck and the external sphincter, was missing, which would indicate that in the course of the operation "this area" adhered to the tissue which was enucleated "and it didn't separate in an ordinary or normal way." In our opinion it was error for the trial court to sustain the objection to the question. The question was proper because counsel obviously sought to explore one possible explanation of the damage to Fehrman's sphincter which Dr. Trangsrud found.

A second ruling on evidence attacked by plaintiffs occurred during the course of Dr. Trangsrud's rebuttal testimony. After he testified that he examined Fehrman with a cystoscope in December, 1959, the doctor was asked this question and gave this answer:

" Q. At that time were you able to find and locate a whole and undamaged sphincter? A. I found a portion of the sphincter, which I found moving and trying to close the flow of urine, as I removed the cystoscope, it should properly be called a remnant."

Dr. Smirl's counsel objected and moved that the answer be stricken because "this doctor cannot see the external sphincter by his cystoscopy examination." The trial court then asked, "Can you see the sphincter by this examination, doctor?" Dr. Trangsrud replied, "You cannot see the sphincter." The trial court then struck the previous answer, which counsel had moved be stricken, and instructed the jury to disregard it. It does not appear from the record whether the ring of muscle constituting the external sphincter forms part of the wall tissue of the prostatic urethra, or whether it lies entirely outside such wall tissue. Nevertheless, the record at the time of the foregoing ruling clearly established that an examination by cystoscope enabled the physician to determine something of the condition of the sphincter including whether it had been damaged or a portion thereof removed. Dr. Thompson stated in his deposition that from the cystoscopic examination made of Fehrman at the Mayo Clinic it was determined that some of the external sphincter had been removed "by the previous surgical procedure." Dr. Kearns had also testified that he could demonstrate the competency of sphincters by using a cystoscope. We conclude, on the basis of this evidence, that the trial court should not have stricken Dr. Trangsrud's answer merely on the basis of his ambiguous statement, "You cannot see the sphincter." One possible explanation of Dr. Trangsrud's statement is that he could not see the whole of Fehrman's sphincter because part of it was missing. Another possible interpretation, of course, is that drawn by the trial judge that the sphincter cannot be seen by a cystoscope.

A third ruling on evidence attacked by plaintiffs relates to the trial court's overruling an objection made by plaintiffs' counsel to the reading into evidence of the following questions and answers from the deposition of Dr. Thompson:

" Q. Is bladder-neck contracture usually due to negligence or malpractice on the part of the surgeon? A. No.

" Q. Is bladder-neck contracture due to negligence on the part of the surgeon? A. You say is it `usually due,' that is the way of question stands. It is not usually due.

" Q. In your physical examination of this patient at the Mayo Clinic, the laboratory tests that were taken, together with the history that you obtained from Dr. Smirl and the patient, your study and consideration of the X rays and reports of the other doctors of the Mayo Clinic, did you find any evidence of negligence? A. No, sir."

It is urged that these questions and answers were incompetent because they invaded the province of the jury. This court, however, is committed to the principle that expert opinion testimony is not objectionable merely because it covers one of the ultimate facts to be determined by the jury. Kreyer v. Farmers' Co-operative Lumber Co. (1962), 18 Wis.2d 67, 76, 117 N.W.2d 646; Zarnik v. C. Reiss Coal Co. (1907), 133 Wis. 290, 301, 113 N.W. 752; and Daly v. Milwaukee (1899), 103 Wis. 588, 590, 79 N.W. 752. See also 7 Wigmore, Evidence (3d ed.), p. 18, sec. 1921. Therefore, the overruling of the objection by the trial court was proper. The trial court was careful to instruct the jury that the weight of the expert, medical-opinion evidence was for the jury atone, and that such opinion testimony is subject to the same rules of credit or discredit as is the testimony of other witnesses.

Error in Instructions Given.

Plaintiffs also attack several of the instructions included in the trial court's charge to the jury. The first of these read as follows:

"You are further instructed that it is the duty of the patient to follow the reasonable instructions and submit to the reasonable treatment prescribed by his physician or surgeon. If he fails in his duty, and his act or omission directly contributes to the injury or disability, he cannot maintain an action for malpractice against his physician or surgeon, who is also guilty of an act or omission in treating the case."

This instruction was included among the specific instructions having to do with the jury's answering Question One of the special verdict concerning the standard of care observed by defendant Smirl. It obviously has no bearing on this question of the verdict because it concerns a possible issue of contributory negligence on the part of Fehrman. Thus, this instruction had no proper place in the charge because no question on contributory negligence was included in the special verdict. It still would be improper even if given with respect to a specific question on contributory negligence, because under sec. 331.045, Stats., contributory negligence is not a bar to recovery unless such contributory negligence equals that of the person against whom recovery is sought. Furthermore, because of use of the phrase "cannot maintain an action for malpractice," this instruction is highly objectionable because it tends to inform the jury of the legal effect of their answer to a question of the special verdict.

Two other attacked instructions, which were given with respect to the jury's answering Question One of the special verdict, were also objectionable because couched in terms which tended to inform the jury of the legal effect of answering Question One of the special verdict "Yes." One such instruction stated, "In order to hold him [Dr. Smirl] liable, the burden is upon the plaintiffs to show that he failed in the requisite degree of care and skill." The other commenced, "Before the plaintiff can recover in such an action . . ."

Res Ipsa Loquitur.

Plaintiffs' counsel raised the issue that plaintiffs were entitled to the benefit of the doctrine of res ipsa loquitur by requesting an instruction grounded on that doctrine. The trial court refused to give the instruction apparently on the ground that this court had held the doctrine of res ipsa loquitur inapplicable in malpractice cases against physicians. This was so held in Kuehnemann v. Boyd (1927), 193 Wis. 588, 592, 214 N.W. 326, 215 N.W. 455. Cf. Vale v. Noe (1920), 172 Wis. 421, 179 N.W. 572. The appellant plaintiff in Ahola v. Sincock (1959), 6 Wis.2d 332, 94 N.W.2d 566, sought to have this court reverse its prior holding that res ipsa loquitur was inapplicable to medical malpractice cases. Nevertheless, because plaintiff in the Ahola Case had failed to request an instruction grounded on res ipsa loquitur in the trial court, this court ruled that the applicability of this doctrine to that medical malpractice case would not be considered. The cases from other jurisdictions are split on the question of whether res ipsa loquitur may properly be invoked in malpractice cases brought against physicians. Annos. 82 A.L.R.2d 1262, and 162 A.L.R. 1265.

The procedural effect of res ipsa loquitur in Wisconsin is that of a permissible inference rather than rebuttable presumption. Weggeman v. Seven-Up Bottling Co. (1958), 5 Wis.2d 503, 509, 93 N.W.2d 467, 94 N.W.2d 645, and Ryan v. Zweck-Wollenberg Co. (1954), 266 Wis. 630, 649, 64 N.W.2d 226. As a permissible inference, the effect of the doctrine of res ipsa loquitur is merely to permit the jury to draw a reasonable inference from circumstantial evidence. It would seem to logically follow from this that situations may arise in medical malpractice actions in which it will be proper to invoke the doctrine of res ipsa loquitur. We can perceive of no justification for adhering to the rule that res ipsa loquitur may never be applied in this type of case, and Kuehnemann v. Boyd, supra, is overruled in so holding. Nevertheless, this does not mean that an instruction embodying the doctrine of res ipsa loquitur is proper in every medical malpractice case.

The difficulty arises in determining the circumstances which make such an instruction either proper or improper. The general rule is that the doctrine of res ipsa loquitur may be invoked in medical malpractice actions only where a layman is able to say as a matter of common knowledge that the consequences of the professional treatment are not those which ordinarily result if due care is exercised, and that the doctrine is not applicable when expert medical testimony is required to show negligence on the part of the practitioner. Anno. 82 A.L.R.2d 1262, 1274. Those situations in which common knowledge of laymen has afforded a proper basis for invoking res ipsa loquitur in medical malpractice actions are summarized in Prosser, Law of Torts (2d ed.), pp. 210, 211, sec. 42, as follows:

"There are, however, some medical and surgical errors on which any layman is competent to pass judgment and conclude from common experience that such things do not happen if there has been proper skill and care. When an operation leaves a sponge in the patient's interior, or removes or injures an inappropriate part of his anatomy, or when a tooth is dropped down his windpipe, or he suffers a serious burn from a hot-water bottle, or when instruments are not sterilized, the thing speaks for itself without the aid of any expert's advice."

Typical cases illustrating injury to an inappropriate part of the anatomy lying without the operative field wherein res ipsa loquitur was invoked, grounded upon the common knowledge of laymen, are Ybarra v. Spangard (1944), 25 Cal.2d 486, 154 P.2d 687, 162 A.L.R. 1258 (plaintiff's shoulder injured during appendectomy); Frost v. Des Moines Still College (1957), 248 Iowa 294, 79 N.W.2d 306 (plaintiff's stomach burned while being prepared for a back operation); and Jensen v. Linner (1961), 260 Minn. 22, 108 N.W.2d 705 (patient received severe burn to leg just above ankle as a result of phenol dripping thereon in operating room during hysterectomy and appendectomy). Those cases are readily distinguishable from the instant case where the external sphincter was only about one and a half inches from the prostate gland being operated on. Cf. Dees v. Pace (1953), 118 Cal.App.2d 284, 257 P.2d 756 (fistula of the bladder developed following hysterectomy). It does not lie within the field of common knowledge of laymen that injury to the sphincter ordinarily does not occur if due care is exercised by the surgeon performing the suprapubic prostatectomy.

Plaintiffs urge that permanent urinary incontinence following a suprapubic prostatectomy on a fifty-three-year-old man is so rare an occurrence as to justify invocation of res ipsa loquitur. Some California cases have held an instruction on res ipsa loquitur proper where the inference of negligence is grounded on unusual result. Typical of these cases is Wolfsmith v. Marsh (1959), 51 Cal.2d 832, 337 P.2d 70, 82 A.L.R.2d 1257. In that case a physician during the course of treatment injected a drug into the inner aspect of plaintiff's knee. A thrombosis developed and a "slough ulcer" appeared at the injection site — a highly unusual result. In its opinion the California court stated (p. 835):

" It is a matter of common knowledge among laymen that injections in the arm, as well as other portions of the body, do not ordinarily cause trouble unless unskillfully done or there is something wrong with the serum." (Emphasis supplied.)

That part of the holding in Wolfsmith v. Marsh, supra embodied in the above-quoted extract has been severely criticized by Rubsamen, Res Ipsa Loquitur in California Medical Malpractice Law — Expansion of a Doctrine to the Bursting Point, 14 Stanford Law Review (1962), 251 (a condensed version of this article appears in Personal Injury Commentator, 1962 Annual, 250) The author, who is the holder of both M. D. and LL.B. degrees, states that the California court's statement in the Wolfsmith Case is in error because of the universal recognition among physicians of the likelihood of untoward and unpredictable reactions to many sorts of injected solutions, even though the utmost care attends their use. The author further points out that if physicians are to be held liable for malpractice because of an unusual, untoward result of a procedure or treatment embodying a calculated risk that this may occur then a physician will be likely to adopt a safer method of procedure or treatment even though in his best judgment the one embodying the calculated risk is advisable.

Happily, the California court in the recent case of Siverson v. Weber (1962), 57 Cal.2d 834, 372 P.2d 97, has now abandoned the test of rarity of result as a proper basis for invoking res ipsa loquitur in medical malpractice cases, and has overruled several earlier cases in which this test had been applied. We have found no cases from jurisdictions other than California which have adopted the rarity test, and we decline to do so.

It is our considered judgment that the instant case is not a proper one in which to give a res ipsa loquitur instruction which is worded so as to permit the jury to infer negligence on the part of Dr. Smirl from any fact of common knowledge possessed by laymen.

Although the rule in a majority of other jurisdictions is otherwise, we are of the opinion that an instruction embodying the principle of res ipsa loquitur may be grounded on expert medical testimony in a malpractice case. California so holds. In Siverson v. Weber, supra, the supreme court of that state declared (p. 836):

"As a general rule, res ipsa loquitur applies where the accident is of such a nature that it can be said, in the light of past experience, that it probably was the result of negligence by someone and that the defendant is probably the person who is responsible. . . . [Citations omitted.] In determining whether such probabilities exist with regard to a particular occurrence, the courts have relied on both common knowledge and the testimony of expert witnesses. ( Seneris v. Haas, 45 Cal.2d 811, 824-26 [ 291 P.2d 915, 53 A.L.R.2d 124] . . .) [a medical malpractice case]."

The general rule with respect to res ipsa loquitur in actions grounded on negligence, is stated in Prosser, Law of Torts (2d ed.) p. 202, sec. 42, as follows:

"The requirement that the occurrence be one which ordinarily does not happen without negligence is of course only another way of stating a principle of circumstantial evidence, that the accident must be such that in the light of ordinary experience it gives rise to an inference that someone has been negligent. Where there is no basis of common knowledge for such a conclusion, expert testimony may be a sufficient foundation for it." (Emphasis supplied.)

On principle, we cannot perceive any reason why an exception to this general rule should be made in medical malpractice actions in a jurisdiction such as Wisconsin where the procedural effect resulting from use of res ipsa loquitur is that of a permissible inference rather than rebuttable presumption.

Under the facts of the instant case what form should the res ipsa loquitur instruction take? If Fehrman's external sphincter was injured during the course of either the first or second operations, Dr. Smirl would be deemed in law to be in control of the situation. Therefore, the instruction in the instant case need not mention the element of exclusive control which ordinarily is included in a res ipsa loquitur instruction. See Wis J I — Civil, Part I, 1145. Thus the only other essential element of such an instruction to be covered is that of a result which ordinarily does not occur without negligence. Accordingly, the following would have been a proper instruction to have been given:

"If you find that plaintiff Fehrman's external sphincter was injured during either the first or second operations, and you further find from expert medical testimony in this case that this injury to the sphincter is of a kind that does not ordinarily occur if a surgeon exercises proper care and skill, then you may infer from the fact of such injury to the sphincter that Dr. Smirl failed to exercise that degree of care and skill which surgeons who practice in the city of Waukesha or vicinity usually exercise, unless Dr. Smirl has offered an explanation for the injury to the sphincter which satisfies you that such injury did not occur through any failure on his part to exercise due care and skill."

It will be noted that the qualifying phrase, "in good standing of the same school of medicine," appearing after the word "surgeons" in Question One of the special verdict, has been omitted from the above instruction. We deem that such phrase could also have been omitted from Question One of the special verdict since Dr. Smirl made no claim that the treatment and operative procedures followed by surgeons in good standing in the Waukesha community differed according to the school of medicine to which they belonged or varied from that of plaintiffs' expert medical witness, Dr. Trangsrud.

The requested instruction on res ipsa loquitur which plaintiffs' counsel submitted was improperly worded because, among other deficiencies, it made no mention of expert medical testimony. Therefore, the trial court properly refused to give such requested instruction in the form submitted.

New Trial in the Interest of Justice.

Because of the errors which occurred in the rulings on evidence, and in the instructions, and because we deem plaintiffs were entitled to a proper res ipsa loquitur instruction, we think it probable that justice may have miscarried. Therefore, we exercise our discretionary power under sec. 251.09, Stats., to order a new trial in the interest of justice on all issues except damages. We find the damages fixed by the jury to be reasonable; therefore, there is no necessity that such issue be relitigated. The grounding of the new trial on the exercise of our discretion under sec. 251.09 is not to be interpreted as a holding that the errors committed in rulings on evidence and in the instructions were not prejudicial. Even though none of them standing alone may have been prejudicial, their cumulative effect may very well have been so.

If during the new trial the evidence which allegedly shows negligence on Dr. Smirl's part only concerns injury to the external sphincter, we would recommend submitting an additional question, as the first question of the special verdict, inquiring whether Fehrman's external sphincter was injured in the course of the first or second operations, or the postoperative care. Cf. Sharp v. Milwaukee S. T. Corp. (1963), 18 Wis.2d 467, 481, 118 N.W.2d 905. If such a question is submitted, then the special verdict should be so worded as to direct the jury not to answer the negligence (malpractice) and causation questions if this first question is answered "No."

In conducting the new trial, none of the facts stated herein are to be construed as the "law of the case" or as limiting the scope of the evidence which may properly be admissible during such new trial.

Costs.

Plaintiffs have requested permission, under Supreme Court Rule 10 (sec. 251.264, Stats.), to tax costs for the printing of their entire brief which, exclusive of index and synopsis of argument, consists of 101 pages. Although this court is not inclined to favor long briefs, we grant plaintiffs' request because of the complicated nature of the factual situation which resulted in about 46 pages of their brief being devoted to statement of the facts.

By the Court. — Judgment reversed, and cause remanded for a new trial on all issues except damages. Plaintiffs are granted permission to tax costs for the printing of their entire brief although it exceeds 50 pages in length.

PER CURIAM (on motion for rehearing).

Defendant's brief in support of the motion for rehearing takes exception to this statement appearing at page 17 of our original opinion:

"Dr. Thompson stated in his deposition that from the cystoscopic examination made of Fehrman at the Mayo Clinic it was determined that some of the external sphincter had been removed `by the previous surgical procedure.'"

Dr. Thompson's exact testimony on this point is quoted in the statement of facts at page 12. Defendant contends that subsequent questions and answers in Dr. Thompson's deposition establish that the quoted words, "apparently some of the latter has been removed by the previous surgical procedure," refer to scar tissue and not the external sphincter. While this is a permissible interpretation, we deem the one which we drew is equally tenable. However, if such quoted words be deemed to be ambiguous, the interpretation favorable to plaintiff should have been the one to be considered by the trial court in making the ruling on evidence considered at page 17 of the original opinion. This is so even though it is arguable that the jury later by its verdict may be deemed to have drawn the opposite interpretation.

A more-important point which we have considered on rehearing relates to the recommended instruction on res ipsa loquitur set forth at page 27 of the original opinion. Whether the evidence presented warrants the giving of a res ipsa loquitur instruction always presents a question of law for the trial court to pass on. At the instant trial no medical witness testified directly that the injuring of the external sphincter in performing a prostatectomy constitutes want of ordinary care on the part of the operating surgeon. However, there was medical testimony that in performing a suprapubic prostatectomy the surgeon is careful not to injure the external sphincter. This gave rise to an inference that if the sphincter was injured in the performance of such operation it would constitute a failure to exercise ordinary care thus rendering proper the giving of the recommended res ipsa loquitur instruction.

Whether it will be proper to give a res ipsa loquitur instruction at the new trial will depend on the expert testimony presented.

The motion for rehearing is denied with $25 costs.