concurring in part, and in part dissenting.
I concur with the majority’s disposition of the issues raised by Brianna’s cross-appeal. While I also agree with the majority that there was an issue of fact with respect to the negligence of Weir and Jones, it is my view that their motions for directed verdict should have been granted because there was insufficient evidence to establish a prima facie showing on the issues of proximate cause and damages. I therefore respectfully dissent from that portion of the majority opinion concluding otherwise.
After determining that the evidence as to proximate cause was sufficient to withstand the motions for directed verdict made on behalf of Weir, COG, and Jones, the majority reasons that there is a separate issue as to damages, namely, whether there was sufficient evidence upon which a jury could determine to what degree the alleged damages sustained by Brianna “were caused by the negligence of the defendants.” To resolve this issue, the majority relies upon Ehlinger v. Sipes, 155 Wis. 2d 1, 454 N.W.2d 754 (1990), a case in which the plaintiffs alleged that the defendant physicians had negligently failed to diagnose *666a multiple pregnancy and take appropriate measures to avoid injuries subsequently suffered by the Ehlingers’ twins as a result of their premature birth. The critical issue in Ehlinger was causation, to which the court stated:
We conclude that the evidence in this case was sufficient under current Wisconsin law to present the causation question to the trier of fact. To establish causation in Wisconsin, the plaintiff bears the burden of proving that the defendant’s negligence was a substantial factor in causing the plaintiff’s harm. . . . “The phrase ‘substantial factor’ denotes that the defendant’s conduct has such an effect in producing the harm as to lead the trier of fact, as a reasonable person, to regard it as a cause, using that word in the popular sense.”
(Citation omitted.) Id. at 12, 454 N.W.2d at 758. It was upon this framework that the Wisconsin Supreme Court fashioned the test upon which the majority in this case relies for determining the nature and sufficiency of evidence which the plaintiff was required to present in order to have the issue of causation submitted to the jury.
The problem with grafting the holding in Ehlinger into our law is that unlike Wisconsin, Nebraska generally utilizes a “but for” test for determining proximate cause in a personal injury case. We have held that there are three basic requirements that must be met to establish causation: (1) that “but for” the defendant’s negligence, the injury would not have occurred; (2) that the injury is the natural and probable result of the negligence; and (3) that there is no efficient intervening cause. Johnson v. School Dist. of Millard, 253 Neb. 634, 573 N.W.2d 116 (1998); World Radio Labs. v. Coopers & Lybrand, 251 Neb. 261, 557 N.W.2d 1 (1996); Anderson/Couvillon v. Nebraska Dept. of Soc. Servs., 248 Neb. 651, 538 N.W.2d 732 (1995). As recently noted in Reimer v. Surgical Servs. of the Great Plains, P.C., post p. 671, 605 N.W.2d 111 (2000), we have utilized the “substantial factor” test for proximate cause primarily in cases where the acts of negligence of two or more persons combine to produce a single injury, although one of them alone could not have caused the result. See, e.g., Kudlacek v. Fiat S.p.A., 244 Neb. 822, 509 N.W.2d 603 (1994) (holding that substantial factor test could be *667used in determining whether vehicle manufacturer’s failure to design crashworthy vehicle was proximate cause of passenger’s injuries notwithstanding evidence that driver was negligent); Miles v. Box Butte County, 241 Neb. 588, 489 N.W.2d 829 (1992) (holding that where record established that nurse’s negligence was substantial factor in bringing about harm to patient notwithstanding evidence that treating physician was also negligent, evidence was sufficient to present question of fact as to whether nurse’s actions were proximate cause of injury). Our use of the “substantial factor” test for establishing proximate cause is consistent with the fact that the rule “ ‘was developed primarily for cases in which application of the but-for rule would allow each defendant to escape responsibility because the conduct of one or more others would have been sufficient to produce the same result.’ ” Reimer v. Surgical Servs. of the Great Plains, post at 677, 605 N.W.2d at 781, quoting W. Page Keeton et al., Prosser and Keeton on the Law of Torts § 41 (5th ed. 1984).
In this case, it is alleged that Brianna sustained specific injuries and damages “[a]s a result of the undiagnosed toxemia, preeclampsia, and seizures which [Shelley] suffered, and the premature delivery of her baby.” The jury was initially instructed that “[a] proximate cause is a cause that produces a result in a natural and continuous sequence, and without which the result would not have occurred.” Supplemental jury instruction No. 1 given by the trial court further instructed the jury:
Negligence is a proximate cause if the negligence occurs and produces in a natural and continuous sequence a result, and the result would not have occurred without the negligence. A proximate cause must be a cause from which the damage or injury sued for naturally flows and without which that damage or injury would not have been sustained. It need not, however, be the immediate cause: it is enough that the act complained of set in motion a series of events through which it produced the damage or injury.
Supplemental jury instruction No. 5 contained a further statement regarding proximate cause:
Supplemental Jury Instruction No. 1 as well as the original jury instruction concerning proximate cause attempt to define proximate cause for the jury. As noted in the state*668ment of the case, before a verdict can be entered in favor of the plaintiff a finding must be made by the jury that the negligence was a proximate cause of certain results.
To be a proximate cause the negligence which occurs must produce a result. Stated another way the result would not have occurred but for the negligence. In that regard the negligence need not be the immediate cause of the result. The negligence must be part of a natural and continuous sequence of events and if the negligence was removed from that sequence of events the result would not have occurred.
Generally, an appellate court will dispose of a case on the theories which were presented to the trial court. Schindler v. Walker, 256 Neb. 767, 592 N.W.2d 912 (1999); Reavis v. Slominski, 250 Neb. 711, 551 N.W.2d 528 (1996). It is clear that the case was pled and tried upon the “but for” causation test, and in my view, this court is obligated to determine whether a question of fact as to causation was presented under this test. Thus, with respect to the issue of proximate cause, the pertinent question is whether there is any evidence from which a jury could infer with reasonable medical certainty that Brianna sustained an identifiable injury compensable in damages which would not have occurred but for the negligence of Weir and Jones.
Expert testimony established that a term pregnancy is considered to be between 38 and 42 weeks’ gestation. Brianna was bom at a gestational age of between 25 to 26 weeks, which is considered “extreme prematurity.” Following her birth, she was diagnosed as suffering from numerous medical conditions related to her level of prematurity, which included apnea, bradycardia, retinopathy, bronchopulmonary dysplasia, moderate cerebral palsy, and spastic diplegia. Robertson’s testimony, viewed in a light most favorable to the plaintiff, establishes that but for the negligence of Weir and Jones, Brianna’s birth could have been delayed for a period of 2 to 6 weeks. When asked bis opinion as to whether Brianna would have been “bom disabled if the pregnancy had been prolonged as long as six weeks,” Robertson responded:
Well, given the gestational age that Brianna was delivered at which was 25 weeks, the outside probably would have *669gotten six weeks. I would have expected her to still have some disabilities because she would have been born at less than 32 weeks and that’s — and certainly in 1992, that was kind of the cut off of where you see problems with prematurity. I would expect those disabilities to be less but she may very well have had some disabilities.
Robertson also testified that Brianna would have been less disabled if the appropriate medical measures had been instituted on December 15, 1992.
The sequence of events leading to Brianna’s injuries was placed in motion not by any act or omission by the physicians but by Shelley’s preeclampsia which, according to Robertson, was going on “long before” she was seen by Weir on December 15, 1992. Robertson’s testimony also establishes that Brianna would have been born prematurely with some disabilities in the absence of any negligence on the part of Weir or Jones. However, neither Robertson nor any other witness identified the nature of such disabilities compared to those actually sustained by Brianna, nor was there any testimony as to morbidity expectations for an infant bom at 26 weeks’ gestation compared to one bom at 32 weeks’ gestation, other than general statements that prolonging a pregnancy is advantageous unless there is an indication of fetal distress. In the absence of any evidence differentiating the injuries which Brianna actually sustained from those she would have sustained in the absence of medical negligence, I do not see how a finder of fact could ever identify any specific injury or damage caused by any negligence on the part of the physicians without engaging in speculation and conjecture.
In this regard, I disagree with the majority’s application of David v. DeLeon, 250 Neb. 109, 547 N.W.2d 726 (1996), to the facts of this case. In DeLeon, a person with a preexisting arthritic condition suffered traumatic injuries in a motor vehicle accident. Following McCall v. Weeks, 183 Neb. 743, 164 N.W.2d 206 (1969), in which we adopted the theory of the “eggshell-skull” plaintiff whom the negligent defendant must take as he or she finds, we held that the plaintiff was not “required to provide a precise line between the damages directly related to the accident and any preexisting physical or mental condition ... as a precondition for recovering any damages at all” and that where *670there is evidence that damages were proximately caused by a negligent act, the burden of apportioning damages between the tortious injury and the preexisting condition fell upon the defendant. David v. DeLeon, 250 Neb. at 115, 547 N.W.2d at 730.
The present case does not involve the infliction of a new traumatic injury upon a preexisting physical condition, as in DeLeon, but, rather, the alleged failure of physicians to properly diagnose and treat a progressive prenatal disease process which ultimately led to Brianna’s premature birth and associated injuries. The critical question is whether the injuries were caused by the disease itself or by the fact that it was not diagnosed and treated by Shelley’s physicians. In my opinion, this must be determined under traditional professional liability concepts, including “but for” causation. Generally, the law does not impose liability upon a physician simply because of a patient’s adverse medical outcome. Rather, the party seeking recovery bears the burden of proving, usually through expert testimony, that the physician departed from a generally recognized standard of care and that the deviation was the proximate cause of the injuries alleged. See, McLaughlin v. Hellbusch, 256 Neb. 615, 591 N.W.2d 569 (1999); Doe v. Zedek, 255 Neb. 963, 587 N.W.2d 885 (1999). That being so, it follows that a prima facie showing in a medical negligence action must include evidence distinguishing harm to a patient caused by medical negligence from that which would have occurred in the absence of such negligence in order to establish “but for” causation. In my opinion, the record does not contain sufficient evidence upon which a finder of fact could make this distinction.
I note that some jurisdictions, recognizing the inherent difficulty in proving what would have occurred in the absence of medical negligence, have departed from traditional causation rules to recognize recovery for “loss of a chance” of survival or a better medical outcome. See Robert S. Bruer, Note, Loss of a Chance as a Cause of Action in Medical Malpractice Cases, 59 Mo. L. Rev. 969 (1994). For example, some courts have utilized a “relaxed causation” approach by adopting the Restatement (Second) of Torts § 323 at 135 (1965), which provides:
One who undertakes, gratuitously or for consideration, to render services to another which he should recognize as *671necessary for the protection of the other’s person or things, is subject to liability to the other for physical harm resulting from his failure to exercise reasonable care to perform his undertaking, if
(a) his failure to exercise such care increases the risk of such harm....
See, Thompson v. Sun City Community Hosp., Inc., 141 Ariz. 597, 688 P.2d 605 (1984); Herskovits v. Group Health, 99 Wash. 2d 609, 664 P.2d 474 (1983); Hamil v. Bashline, 481 Pa. 256, 392 A.2d 1280 (1978). Other courts treat loss of a chance as a distinct compensable injury, a theory derived from Joseph H. King, Jr., Causation, Valuation, and Chance in Personal Injury Torts Involving Preexisting Conditions and Future Consequences, 90 Yale L.J. 1353 (1981). See, e.g., Perez v. Las Vegas Medical Center, 107 Nev. 1, 805 P.2d 589 (1991); DeBurkarte v. Louvar, 393 N.W.2d 131 (Iowa 1986). This court has not adopted either of these positions and cannot reach the issue of whether to do so in this case because it was pled and tried under the “but for” theory of causation.
For these reasons, I would reverse, and remand with directions to dismiss.
Connolly, J., joins in this concurrence and dissent.