
215 S.E.2d 89 (1975)
Graham W. DEAN
v.
CAROLINA COACH COMPANY, INC.
No. 59.
Supreme Court of North Carolina.
June 6, 1975.
*91 Teague, Johnson, Patterson, Dilthey & Clay by I. Edward Johnson and Grady S. Patterson, Jr., Raleigh, for plaintiff-appellant.
Smith, Anderson, Blount & Mitchell by James D. Blount, Jr.; Samuel G. Thompson and Michael E. Weddington, Raleigh, for defendant-appellee.
BRANCH, Justice.
Defendant assigns as error the ruling of Judge McKinnon in allowing Dr. Alexander Webb to express his expert opinion in answer to a hypothetical question, which defendant contends was defective by reason of being factually incomplete. By this assignment of error and its Exception No. 7, defendant also argued in the Court of Appeals that the Court's failure to strike the unresponsive answer was error.
The Court of Appeals quoted and based its decision on the following rule found in 1 D. Stansbury, North Carolina Evidence § 137 at 452 (Brandis Rev.):
. . . In framing a hypothetical question the following cautions should be observed:
* * * * * *
2. Include all of the material facts which will be necessary to enable the witness to form a satisfactory opinion. Although it is not necessary to incorporate all [original emphasis] of the facts, the trial judge may properly exclude the witness's answer if the question presents a picture so incomplete that an opinion based upon it would obviously be unreliable. [Emphasis supplied, footnotes omitted.]
As a general rule, a hypothetical question which omits any reference to a fact which goes to the essence of the case and therefore presents a state of facts so incomplete that an opinion based on it would be obviously unreliable is improper, and the expert witness's answer will be excluded. Todd v. Watts, 269 N.C. 417, 152 S.E.2d 448; Schafer v. Railroad, 266 N.C. 285, 145 S.E.2d 887; State v. Thompson, 153 N.C. 618, 69 S.E. 254; Steiger v. Massachusetts Cas. Ins. Co., 273 So.2d 4 (Fla.App.); *92 Smith v. Twin City Motor Bus Co., 228 Minn. 14, 36 N.W.2d 22. However, there is substantial authority to the effect that the interrogator may form his hypothetical question on any theory which can be deduced from the evidence and select as a predicate therefor such facts as the evidence reasonably tends to prove. 31 Am. Jur.2d Expert and Opinion Evidence § 56 at 562; Pigford v. R. R., 160 N.C. 93, 75 S.E. 860.
In Pigford, the plaintiff, an employee of the defendant, stated that he was instructed by his supervisor to load a gondola car with iron rails. He told the supervisor that he had only three men and a boy working with him, and he did not think that he had enough help to load the rails. The supervisor told him to do the best he could. In the process of loading, he felt something "tear loose" when a rail turned over on him. The evidence further tended to show that the plaintiff suffered a serious hernia as a result of the injury.
The record discloses that during the presentation of the plaintiff's case, an expert medical witness was asked the following hypothetical question:
If the jury should find it a fact that he was engaged in loading a car 7½ feet from the ground with 660 pound rails, with a force of three men and a boy, and in pushing the rail up on the car, or in assisting to push it he felt pain in the region of the stomach from which a hernia was subsequently observed by you, state in your opinion what would have caused the appearance of the hernia. I am asking for your professional opinion as to whether the hernia could have been the result of such an act on his part?
The defendant contended that the abovequoted question was erroneous because the evidence tended to show that the plaintiff was using slides which he had prepared himself and that five men were engaged in the work instead of three, as set forth in the question. This Court rejected this contention, and, although conceding that the question was "not as full as it might have been," held that it combined "substantially all the facts" so that the question was "sufficiently explicit for [the expert] to give an intelligent and safe opinion." See also State v. Dilliard, 223 N.C. 446, 27 S.E.2d 85.
The rule relied upon by the Court of Appeals has been considered and somewhat modified by a line of cases represented by State v. Stewart, 156 N.C. 636, 72 S.E. 193. There the defendant, who was charged with murder, objected to a hypothetical question posed as to the cause of death of the victim of the homicide because one fact as to which there was evidence was not incorporated into the question. In rejecting defendant's contention, the Court, inter alia, quoted State v. Holly, 155 N.C. 485, 71 S.E. 450:
"It is not necessary in the statement of a hypothetical question that all the facts should be stated. Opinions may be asked for upon different combinations of facts on the examination in chief and on the cross-examination."
If the defendant thought the fact, which was omitted, would have elicited a different opinion from the witness, it was his right and duty to incorporate it in a question on cross-examination.
The statement in Stewart was amplified in Godfrey v. Power Co., 190 N.C. 24, 128 S.E. 485, by the following language: "It was not incumbent on the plaintiff to include in his [hypothetical] questions all the evidence bearing upon the fact to be proved; the defendants had the right to present other phases of the evidence in counter-hypothetical questions . . . ." Accord: Canney v. Travelers Ins. Co., 110 N.H. 304, 266 A.2d 831.
A leading authority on evidence adopts a view consistent with decisions of this Court:
. . . Some courts have required that all facts material to the question should be embraced in the hypothesis, but this viewpoint seems undesirable because it is likely to multiply disputes as to the sufficiency of the hypothesis, and may tend to *93 cause counsel, out of abundance of caution, to propound questions so lengthy as to be wearisome and almost meaningless to the jury. The more expedient and more widely prevailing view is that there is no rule requiring that all material facts be included. The safeguards are that the adversary may on cross-examination supply omitted facts and ask the expert if his opinion would be modified by them, and further that the trial judge if he deems the original question unfair may in his discretion require that the hypothesis be reframed to supply an adequate basis for a helpful answer. [Footnotes omitted.]
E. Cleary (Gen.Ed.), McCormick's Handbook of the Law of Evidence § 14 at 33-34 (2d ed.). See also 31 Am.Jur.2d Expert and Opinion Evidence § 57; Annotation, 56 A.L. R.3d 300 § 7.
Here, all the evidence disclosed that, prior to the accident, plaintiff had undergone surgery for correction of a hernia. The hypothetical question posed by plaintiff's counsel did not seek Dr. Webb's opinion as to whether the accident caused the hernia but rather sought his opinion as to whether the accident "could or might have aggravated the preexisting condition, that is the preexisting surgical procedures, could or might have aggravated that condition and resulted in the necessary treatment that you gave him?" The testimony of Dr. Whitaker and plaintiff at trial disclosed that the hernia returned and that plaintiff suffered some pain prior to the accident. In this connection plaintiff testified that the hernia "was bulging out a month before the accident, but there was no pain. I said there was not enough pain that I thought I should wear a support." He testified that he had never worn a support until after the accident. This testimony was entirely consistent with a theory that the accident could or might have aggravated the plaintiff's preexisting condition.
Defendant argues that it did not have the opportunity to cross-examine Dr. Webb concerning the omitted fact since the doctor's testimony was taken and offered by deposition. Be that as it may, at trial defense counsel had the opportunity to present other phases of the evidence through counter-hypothetical questions. Defense counsel had the opportunity to cross-examine plaintiff and Dr. Whitaker concerning plaintiff's preexisting condition. In fact, defense counsel did searchingly cross-examine these witnesses so as to make the jury fully cognizant of the reoccurrence of the hernia prior to the accident. Under these circumstances we cannot agree with the holding of the Court of Appeals that the hypothetical question presented a "picture so incomplete that an opinion based on it was misleading to the jury and obviously unreliable." Although the hypothetical question did not present a complete factual background, it did contain sufficient facts to allow Dr. Webb to express an intelligent and safe opinion as to whether the accident on 13 May 1971 aggravated plaintiff's preexisting condition.
We are thus brought to the answer elicited by the hypothetical question. Under this same assignment of error defendant argued in the Court of Appeals that Dr. Webb's answer to the hypothetical question was unresponsive and that he seriously prejudiced defendant's case by improperly answering the ultimate issue before the jury, i. e., what happened to plaintiff in the automobile accident on 13 May 1971. The Court of Appeals did not consider this contention, and defendant, the prevailing party in that Court, did not discuss it in his Supplemental Brief. Defendant did, however, specifically note that the Court of Appeals addressed itself to only one of its assignments of error and urged this Court to consider all assignments of error argued before the Court of Appeals. The hypothetical question and the answer to it are inextricably tied, and we consider it fair and proper to consider this portion of defendant's argument.
An expert witness may base his opinion upon facts within his own knowledge *94 or upon the hypothesis of the finding of certain facts recited in the question. Summerlin v. Railroad, 133 N.C. 550, 45 S.E. 898; however, an expert is not competent to testify as to a causal relation which rests upon mere speculation or possibility. Lockwood v. McCaskill, 262 N.C. 663, 138 S.E.2d 541.
Here the answer given by the expert was unresponsive, and defense counsel properly preserved his objection by objecting to the hypothetical question and immediately moving to strike the unresponsive answer. See Highway Commission v. Black, 239 N.C. 198, 79 S.E.2d 778; State v. Mays, 225 N.C. 486, 35 S.E.2d 494. Initially, we note that the hypothetical question asked for an opinion as to whether a condition could or might have been aggravated by the accident of 13 May 1971. The answer ". . . that a man can go along for years with an inguinal hernia . . . without difficulty until he has some aggravated assault to it, and that is what happened here," in effect, stated that an aggravated assault caused plaintiff's difficulty. The prejudicial effect of this answer was compounded when Dr. Webb on cross-examination again unresponsively stated, "We do know his acute symptoms were brought about by an automobile accident by his history." Again defendant's motion to strike the answer was denied. Immediately thereafter Dr. Webb on cross-examination admitted that there was no reference in his records as to when plaintiff's groin pain started and that there was no reference at all to an automobile accident in his notes. Examination of the hypothetical question discloses that there was no mention of an automobile accident.
The record reveals that Dr. Webb was well qualified to state that plaintiff had a hernia when he examined and treated him. However, his unresponsive, unequivocal statement as to causation was not within his personal knowledge; neither was it contained in the patient's medical history; nor did the answer rest upon the hypothesized facts recited in the hypothetical question. It is obvious that Dr. Webb had no factual basis for his statement to the effect that plaintiff's injury resulted from an aggravated assault. Clearly, the answer to the hypothetical question invaded the province of the jury and was, at best, based on conjecture and speculation. We therefore hold that the failure of the trial judge to allow defense counsel's motion to strike Dr. Webb's answer to the hypothetical question was error prejudicial to defendant.
Modified and affirmed.
