Opinion
THOMPSON, J.In this appeal from a judgment for defendants in a medical malpractice action, appellant contends: (1) the trial court erroneously directed a verdict in favor of defendants Greenberg and King; (2) the court improperly instructed the jury on the doctrine of res ipsa loquitur as applicable to defendant Northridge Hospital Foundation; and (3) the court improperly limited the effect of an answer to interrogatories filed by Northridge. We conclude that the trial court prejudicially erred in instructing on the applicability of conditional res ipsa loquitur to the case at bench and accordingly reverse the judgment as to Northridge Hospital. We affirm the judgment in favor of Greenberg and King.
On August 24, 1969, appellant was admitted to Northridge Hospital for delivery of her second child. She was under the care of Doctors Schein and Greenberg. Dr. Greenberg administered a saddle block anesthetic which proved ineffective. Herbert J. King, a registered nurse anesthetist, administered a general anesthetic. Appellant was delivered of a healthy baby girl by Dr. Greenberg without apparent complications. In the course of her confinement and after delivery, appellant was administered several injections in her right buttock by nurses, agents of Northridge Hospital and solely under its control. Appellant was discharged from the hospital on August 27.
On August 30, appellant experienced severe pain in her right hip which prevented her from walking. The pain became worse and appellant developed chills and fever. Dr. Greenberg readmitted her to Northridge Hospital that day. Appellant’s temperature was 101 degrees. She had objective evidence of induration and marked tenderness in the right buttock and a slight “shift of blood count to the left.” A tentative diagnosis of postpartum pyelonephritis was dispelled by testing, and Dr. Greenberg requested consultation of an orthopedist. His tentative diagnosis was that appellant had developed “a small deep-seated abscess in the region of the previous injections into the right buttock.” Treatment with antibiotics reduced the fever, and appellant was again discharged from the hospital. Dr. Greenberg’s diagnosis upon appellant’s discharge *127was “acute peripheral neuritis, probably secondary to injections that she received in the right buttocks [a/c] during labor and postpartum.”
Treatment of appellant continued after her discharge from Northridge Hospital. Dr. Greenberg and a treating radiologist, orthopedist, and neurosurgeon agreed that appellant suffered from spinal osteomyelitis (degeneration of the bone) and probable involvement of the sciatic nerve due to an infection originating in the tissue of the right buttock and spreading to the bone. All agreed also that the probable cause of the infection lay in the injections administered to appellant while she was in the hospital.
Appellant filed a complaint in malpractice commencing the case at bench. She named as defendants Northridge Hospital, Drs. Schein and Greenberg, and Mr. King. Her evidence at trial consisted of testimony of the various treating physicians in the tenor of the facts recited above. She also produced competent testimony that an injection given in the right buttock would not, without negligence, result in the condition from which appellant suffered. The trial court limited the admissibility of an answer to interrogatories filed by Northridge Hospital to the effect that Dr. Greenberg had supervised and controlled the conduct of the nurses in administering the injection. It ruled that the answer was admissible against the hospital but not against Dr. Greenberg. The trial court granted a nonsuit as to Dr. Schein which is not questioned on this appeal. It heard evidence presented by Northridge Hospital in the form of expert opinion of an internist who had not examined appellant that appellant did not acquire the infection as a result of an injection. The expert opinion was based upon the assumption that an injection would not be given by a competent nurse in an area of the buttock in which the infection occurred. The expert called by Northridge Hospital presented the thesis that the injuiy to appellant was probably caused by an infection of the uterus incident to childbirth.
The trial court granted a directed verdict as to Dr. Greenberg and Mr. King. Over appellant’s assertion that she was entitled to an unconditional res ipsa loquitur instruction or, alternatively, that if a conditional instruction were given the only condition to the application of the doctrine not established as a matter of law was whether the injury is of a kind which ordinarily does not occur in the absence of negligence, the trial court instructed the jury in terms of BAJI Nos. 6.35 and 4.02 (1970 Revision).1 Those instructions permitted the jury to infer negligent *128conduct on the part of Northridge Hospital from the injury to. appellant only if the jury first found that the injury was of a kind that ordinarily does not occur in the absence of negligence, the injury was caused while appellant was under the exclusive care or control of the hospital, and the injury was not due to any voluntary action or contribution on her part.
After it had retired to deliberate, the jury asked that it be read the answer of Northridge Hospital to interrogatories propounded to it by appellant. One of those answers claimed that the nurses were “under the direction or supervision” of Dr. Greenberg in administering the injections. The answer was read to the jury in response to its request and over appellant’s objection. The jury returned a verdict for Northridge Hospital and against appellant. This appeal from the judgment entered on that verdict and the directed verdicts in favor of Dr. Greenberg and Mr. King followed.
No error is present in the judgments for Dr. Greenberg and Mr. King. Appellant’s sole theory of recovery is that her injury resulted from the negligent administration of injections to her right buttock. Neither Dr. Greenberg nor Mr. King administered any injection there and there is no evidence that either was the principal of any nurse who administered that treatment.
Nor did the trial court err in excluding as evidence against Dr. *129Greenberg the interrogatory answer of Northridge Hospital which, if admissible against him, would have cured the fatal deficiency. “The answers of one party . . . elicited in response to interrogatories ... cannot be used as evidence against [another] party . . . .” (Petersen v. City of Vallejo, 259 Cal.App.2d 757, 776 [66 Cal.Rptr. 776]; Code Civ. Proc., §§ 2030, subd. (b), 2016, subd. (d).)2
The court, however, erred in instructing the jury on the application of the doctrine of res ipsa loquitur.
The doctrine transfers to the defendant the burden of producing evidence negating negligence or proximate cause, and permits an inference of negligence and proximate cause even in the situation where the defendant carries his burden. (Evid. Code, § 646.) In California, the doctrine is applicable where: (1) the injury is of a kind which ordinarily does not occur in the absence of negligence; (2) the injury is caused by an instrumentality within the exclusive control of the defendant or group of defendants; and (3) the injury was not due to any voluntary action or contribution by the plaintiff. (Ybarra v. Spangard, 25 Cal.2d 486, 489 [154 P.2d 687, 162 A.L.R. 1258].) Stated less mechanically, a plaintiff suing in a personal injury action is entitled to the benefit of res ipsa loquitur when: “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.” (Zentz v. Coca Cola Bottling Co., 39 Cal.2d 436, 446 [247 P.2d 344]; see also Bardessono v. Michels, 3 Cal.3d 780, 788, fn. 5 [91 Cal.Rptr. 760, 478 P.2d 480, 45 A.L.R.3d 717].)
“Where the facts giving rise to the doctrine [of res ipsa loquitur] are established as a matter of law but the defendant has introduced evidence sufficient to sustain a finding either of his due care or of a cause for the accident other than his negligence, the presumptive effect of the doctrine vanishes. Except in those rare cases where the inference is dispelled as a matter of law, the court may instruct the jury that it may infer from the established facts that negligence on the part of the defendant was a proximate cause of the accident. . .. [1Í]... The defendant may introduce evidence that both attacks the basic facts that underlie the doctrine of res *130ipsa loquitur and tends to show that the accident was not caused by his failure to exercise due care. Because of the evidence contesting the presumed conclusion of negligence, the presumptive effect of the doctrine vanishes, and the greatest effect the doctrine can have in the case is to support an inference that the accident resulted from the defendant’s negligence. [V] In this situation, the court should instruct the jury that, if it folds that the basic facts have been established by a preponderance of the evidence, then it may infer from those facts that the accident was caused because the defendant was negligent. . . .” (Law Revision Com. comment on Evid. Code, § 646; see also Albers v. Greyhound Corp., 4 Cal.App.3d 463, 474 [84 Cal.Rptr. 846].)
It follows that where part of the facts basic to the application of the doctrine of res ipsa loquitur is established as a matter of law but that others are not, the court should instruct that application of the doctrine by the jury depends only upon the existence of the basic facts not conclusively established. (See Roddiscraft, Inc. v. Skelton Logging Co., 212 Cal.App.2d 784, 794 [28 Cal.Rptr. 277]; Kite v. Coastal Oil Company, 162 Cal.App.2d 336, 344 [328 P.2d 45].)3
Here the evidence established as a matter of law that Northridge Hospital was in exclusive control of the instrumentality that caused the injury and that the injury was not due to voluntary action or contribution by appellant. Stated in the terms of the less mechanistic formula, the evidence establishes as a matter of law that if the injury was caused by negligence Northridge Hospital was probably the entity responsible. The record is uncontradicted that no one other than Northridge Hospital and its agents had anything to do with the conduct causing injury to appellant. The trial court confirmed that proposition by granting a nonsuit to Dr. Schein and a directed verdict to Dr. Greenberg and Mr. King. There is not the slightest evidence that anything that appellant did in any way contributed to her injury. (See Shahinian v. McCormick, 59 Cal.2d 554, 559-560 [30 Cal.Rptr. 521, 381 P.2d 377].)
The trial judge, however, placed before the jury as issues of fact questions which the record established as matters of law. He instructed in the three factor formula of conditional res ipsa loquitur, leaving it to the jury to decide whether two of the conditions to the application of the *131doctrine were present when in fact they were established conclusively. While its sole task in determining the basis for the inferences permitted by res ipsa was consideration of the question of whether the injury was one that ordinarily would not occur in the absence of negligence, the juiy was invited by the instruction to speculate that Northridge Hospital was not in exclusive control of the injections or that some action of appellant herself contributed to the injury. Thus the trial court erred in its instruction to the jury by erroneously increasing appellant’s burden.
The error was prejudicial. Prejudicial error is established where the record as a whole reveals a reasonable probability that a result more favorable to the appealing party would have been reached in the absence of the error. (People v. Watson, 46 Cal.2d 818, 836 [299 P.2d 243].) “Generally speaking if it appears that error in giving an improper instruction was likely to mislead the juiy and thus to become a factor in its verdict, it is prejudicial and ground for reversal.... ‘[W]here it seems probable that the jury’s verdict may have been based on the erroneous instruction prejudice appears and [the reviewing] court “should not speculate upon the basis of the verdict.” ’ ” (Henderson v. Harnischfeger Corp., 12 Cal.3d 663, 670 [117 Cal.Rptr. 1, 527 P.2d 353], quoting Robinson v. Cable, 55 Cal.2d 425, 428 [11 Cal.Rptr. 377, 359 P.2d 929].)
Here the instruction was likely to mislead the jury and to become a factor in its verdict. The jury was informed that there were factual issues relating to the exclusive control by Northridge Hospital of the procedure which appellant claimed was the cause of her injury and to appellant’s own contribution to her condition. Here, there also is a strong indication that the jury’s verdict may have been based on the erroneous instruction. During its deliberations, the jury asked that Northridge’s self-serving and hence inadmissible answers to interrogatories going to the subject of control and supervision by Dr. Greenberg of the giving of injections by the nurses be reread. They were read over appellant’s objection. It is fairly inferred from the jury’s interest in those answers that the jury members were considering the possibility that Northridge Hospital was not in exclusive control, when it was as a matter of law.
Focusing on the opinion evidence of the defense expert, Northridge Hospital argues that it has established such a strong case of absence of negligence that no miscarriage of justice resulted from the defense verdict no matter how erroneous the instructions to the jury may have been. The argument ignores the fact that the expert’s testimony was *132based upon his assumption that an injection was not administered to appellant in a place where it could have caused the infection. Misplacement of the injection was, however, one of the very acts of negligence which the hospital was required to go forward to rebut if the doctrine of res ipsa loquitur is applicable.
Taking the opposite tack, respondent Northridge Hospital also argues that the record is so clear that it was in exclusive control of the injection procedure and that appellant did not herself contribute to the injury that it must be assumed that the jury did not question the existence of those ultimate facts. That argument invites us to indulge in the speculation concerning the jury’s thought process that has been condemned by our Supreme Court. (Henderson v. Harnischfeger Corp., supra, 12 Cal.3d 663, 670.)
In summary, the record of the case at bench discloses a close case in which an instruction likely to mislead was given to the jury and where it is probable that the verdict may have been based upon the instruction. Prejudicial error is thus established.
The judgment is reversed as to respondent Northridge Hospital Foundation and otherwise affirmed. Appellant to recover her costs from Northridge Hospital Foundation. Respondents Greenberg, Schein and King to recover their costs from appellant.
Lillie, Acting P. J., concurred.
“BAJI 6.35 MEDICAL MALPRACTICE—conditional RES IPSA LOQUITUR [1|] *128You must decide the following questions] concerning the injury involved in this case: [H] Is it the kind of injury which ordinarily does not occur in the absence of negligence? [H] [Whether the injury is one which ordinarily does not occur in the absence of negligence is to be determined from the evidence presented in this trial by physicians and surgeons called as expert witnesses.] [H] Was the injury caused while the plaintiff was exclusively under the care or control of the defendant? [The plaintiff is not required to identify the particular agency or instrumentality which caused the injury if he is unable to do so because of his physical condition at the time the treatment was administered.] [H] Was the injury due to any voluntary action or contribution on the part of the plaintiff which was the responsible cause of his injury? [11] If, and only if, you find that the plaintiff’s injury was of a kind which ordinarily does not occur in the absence of negligence; that it was caused while the plaintiff was exclusively under the care or control of defendant; and that it was not due to any voluntary action or contribution by the plaintiff which was the responsible cause of his injury, you are instructed as follows:”
“BAJI 4.02 [1970 REVISION) RES IPSA LOQUITUR—WHERE ONLY A PERMISSIBLE INFERENCE OF NEGLIGENCE [11] From the happening of the [injury] involved in this case, you may draw an inference that a [legal] cause of the occurrence was some negligent conduct on the part of the defendant. [H] However, you shall not find that a [legal] cause of the occurrence was some negligent conduct on the part of the defendant unless you believe, after weighing all the evidence in the case and drawing such inferences therefrom as you believe are warranted, that it is more probable than not that the occurrence was caused by some negligent conduct on the part of the defendant.”
Since the date of Petersen v. City of Vallejo, Code of Civil Procedure section 2030 has been amended to require service of copies of interrogatories and answers on all parties who have appeared “solely for their information.” Because of the limited purpose of service of interrogatories and answers, the amendment does not affect the rationale of Petersen.
Because we here conclude that the conditional res ipsa loquitur instruction as given was prejudicially erroneous, we dq not reach the issue of appellant’s right to an unconditional instruction on the doctrine. That issue must be determined on the basis of the evidence presented on retrial.