The question to be decided in this case, which is closely akin to a medical malpractice suit, is whether there is any evidence to support a finding that the negligence of the defendants was a proximate cause of plaintiff’s injuries and damage. Plaintiff is Dennis H. Lenger, who underwent surgery in a hospital operated by Physician’s General Hospital, Inc. Defendants are Hospital, Mrs. Pauline Jones, who attended plaintiff as a nurse for several days, and Mrs. Berdena Hightower, d/b/a Adamson Nurses Registry, who sent Mrs. Jones to *705Hospital. Their motion for instructed verdict was granted by the trial court, and the Court of Civil Appeals affirmed. 438 S.W.2d 408. We affirm the judgment of the Court of Civil Appeals.
There is little dispute as to the events leading to the suit. Plaintiff entered the hospital on August 3, 1965. He was a patient of Dr. Frank Rainone, who is a surgeon in Arlington. After a number of a diagnostic tests, Dr. Rainone operated on August 10. A colon resection was performed at that time to remove a cancerous growth located in the middle transverse section of the colon. Following the operation and a brief stay in the recovery room, plaintiff was removed to a private room. He was under morphine sedation, was being fed intravenously, and had a Levin tube inserted through the nose into the stomach, which was being evacuated by a suction pump. Dr. Rainone had ordered that plaintiff receive nothing by mouth and that he be attended by private nurses around the clock.
As a result of erroneous instructions given by Hospital’s night charge nurse, the dietary department sent trays of solid food to plaintiff’s room for each of the three meals on August 12. Plaintiff protested eating this food and requested that Dr. Raino-ne be called. Mrs. Jones, who was attending plaintiff at the time, stated that she would not bother the doctor and assured plaintiff that the food would not have been sent to his room if it were not all right for him to eat. Plaintiff then ate most of the breakfast. After eating he felt as though he had gas on his stomach, which was quite sore from the surgery. Plaintiff also ate the noon meal. That afternoon it again seemed that he had gas on his stomach and the Levin tube would not drain. The tube was irrigated several times By Mrs. Jones with the assistance of Mrs. Kathryn Garnett, Supervisor of Nurses for Hospital. Mrs. Garnett said the tube had been clogged by the food. The food was not removed from plaintiff’s stomach. That evening he “felt terrible” and refused to eat the supper meal that was delivered to his room.
Plaintiff was given nothing more by mouth until August 13 when he was allowed to have a few ice chips, primarily to moisten his mouth and make him more comfortable. The Levin tube was removed on August 14, and the following day plaintiff was given water, ice chips and 7-Up. On August 16 he was placed on a full liquid diet. This diet included jello, beef broth, some of the thicker soups, certain cooked cereals, and soft drinks.
Plaintiff felt better for several days after August 12. During this period he was up from time to time, sat on the bed, moved around, and went to the bathroom. He began feeling worse on August 16, and his condition continued to deteriorate until Dr. Rainone operated again on August 20. It was then discovered that the two ends of the colon, which were sutured together during the first operation, had come completely apart. There was gas and fecal material in the abdominal cavity, and part of the small intestine had worked up into the colon at the point of separation. The small intestine had become so obstructed that it was filled with gas and its own secretions.
The colon could not be resutured because of the infection, and Dr. Rainone performed a double-barreled colostomy. On October 12 Dr. Rainone performed a third operation to undo the double-barreled colostomy. The remaining portion of the colon on the right side was then removed and the small intestine was joined to the descending colon on the left side of the body. Plaintiff was released from the hospital on October 30 and returned ■ to work about five months later.
The evidence will support findings that defendants were negligent in the several respects alleged and that their negligence is causally related to plaintiff’s eating the solid food on August 12. There is also evidence to warrant the conclusion that a person of ordinary prudence should have *706foreseen that his eating the solid food at that time and under the circumstances might result in injury of some kind. The question here is whether the evidence will support the further conclusion that the two •meals eaten by plaintiff were a cause in fact of his subsequent difficulties.
The proof that must be made to establish causal .relation is easily stated in general terms, but it is often difficult to determine whether a sufficient showing has been made to warrant submission of the issue to the jury. Since liability cannot be made to turn upon speculation or conjecture, it is essential that the evidence show at least a reasonable probability that plaintiff’s complications were caused by defendants’ negligence. Insurance Co. of North America v. Myers, Tex.Sup., 411 S.W.2d 710. “The proof must establish causal connection beyond the point of conjecture. It must show more than a possibility. Verdicts must rest upon reasonable certainty of proof. Where the proof discloses that a given result may have occurred by reason of more than one proximate cause, and the jury can do no more than guess or speculate as to which was, in fact, the efficient cause, the submission of such choice to the jury has been consistently condemned by this court and by other courts.” Ramberg v. Morgan, 209 Iowa 474, 218 N.W. 492. See also Bowles v. Bourdon, 148 Tex. 1, 219 S.W.2d 779.
The trier of fact is usually allowed to decide the issue of causation in cases of this nature: (1) when general experience and common sense will enable a layman fairly to determine the causal relationship between the event and the condition; (2) when scientific principles, usually proved by expert testimony, establish a traceable chain of causation from the condition back to the event; and (3) when probable causal relationship is shown by expert testimony. See Parker v. Employers Mutual Liability Ins. Co., Tex.Sup., 440 S.W.2d 43. This does not mean that the court, in determining whether the issue should be submitted to the jury, must consider only evidence of one type to the exclusion of that falling into the other categories. In Insurance Co. of North America v. Kneten, Tex.Sup., 440 S.W.2d 52, the claimant suffered a heart attack shortly after sustaining an electric shock. The medical expert would only say that it was a strong possibility that the shock precipitated the attack, but his testimony did not rule out a medical relationship between the two. It was held that in view of the prompt onset of the attack following an event capable of causing it, the jury could reasonably conclude that the shock did, in fact, cause the attack. Expert testimony was thus relied upon to establish a possible causal relationship, but the jury was allowed to make the ultimate determination on the basis of general experience and common sense.
Turning now to the evidence in this case, Dr. Rainone was the only expert medical witness. He was quite positive in some of his statements and conclusions. It is his opinion that a hole or opening had first appeared in the mesentery or mesoco-lon, which is the tissue joining the colon to the abdominal wall. This hole or opening, which should not have been there, was underneath the colon at the point where the ends were sutured during the first operation. The small intestine had inserted or forced itself into the hole or opening and become obstructed. When the small intestine became obstructed it filled with gas and its own secretions. This caused pressure underneath the colon and forced the sutured ends of the colon apart. The obstruction of the small intestine was mechanical rather than functional. It was caused in this instance by the fact that the suture of the mesentery came apart for some reason.
Our question thus narrows to whether there is evidence to show that, in reasonable probability, the two meals were a cause in fact of the opening in the mes-entery. Dr. Rainone stated that he did not know what caused it to come apart. At *707that point the trial court sustained defendants’ objection and refused to allow the witness to testify concerning the possible causes of the separation. This was error. As pointed out in Otis Elevator Co. v. Wood, Tex.Sup., 436 S.W.2d 324, the rule of “reasonable medical probability” relates to the showing that must be made to support an ultimate finding of fact and not to the standard by which the medical expert must testify. Expert testimony concerning the possible causes of the condition in question will often assist the trier of fact in evaluating other evidence in the case. If the witness were permitted to state his opinion only in terms of medical probabilities, moreover, the court and jury would have no opportunity to decide the case on the basis of the substance rather than the form of his testimony. In disposing of the present appeal, we consider all of Dr. Rai-none’s testimony, including that which was admitted and that which is found in the bill of exception.
The witness stated that the possible causes of the opening in the meso-colon are: (1) failure of the stitches to hold; (2) tension on the suture lines resulting from the twisting or other movements of plaintiff’s body while he was walking, sitting up or turning over in bed; and (3) the solid food eaten on August 12. He did not regard causal relationship between the solid food and the subsequent complications as an unlikely possibility. “It would not be a great or overwhelming possibility, but there is a distinct possibility that this could occur * * * it would be a real possibility. If I didn’t believe this, I wouldn’t put a tube in anyone’s stomach.” Dr. Rainone insisted, however, that there is no way he could reasonably state what caused the meso-colon to come apart. This complication can occur despite all the precautions surgeons can take. “It’s just as reasonable one thing could have caused it as another.” The witness did not know whether the small intestine would have become obstructed if plaintiff had been given no food.
This evidence is not enough in itself to support a finding of causation. As pointed out in Parker, expert testimony that the event is a possible cause of the condition cannot ordinarily be treated as evidence of reasonable medical probability except when, in the absence of other reasonable causal explanations, it becomes more likely than not that the condition did result from the event. Dr. Rainone said nothing that can fairly be taken as an indication that he regarded the solid food as the more likely of the several possible causes.
Plaintiff insists that in view of the sequence of events, a lay jury could reasonably determine the issue of causation on the basis of general experience and common sense. Dr. Rainone supplied additional information that is relevant to this contention. The transverse colon is immediately under the stomach, and the weight of the solid food would cause the stomach to go down on the anastomosis. Plaintiff’s stomach was not functioning properly at that time. It was in a state of ileus, which apparently is a condition of temporary, partial paralysis. This condition generally lasts “from a day and a half to two or three days and sometimes up to five days after an operation.” The witness expressed the opinion, however, that the ileus was in existence when plaintiff was given the liquid diet on August 16. He wanted plaintiff’s stomach to remain empty until the ileus was resolved. If food or fluid or air is allowed into the stomach while the patient has the ileus, a whole series of complications can develop. Patients with ileus are prone to swallow air, and “they get the small intestine full of air, the stomach and small intestine which is unable to pass except in small increments and gradually causes a distention of the abdomen.” This causes the patient a great deal of distress. It can cause obstructions, tension on the suture lines, a variety of complications. “The main reason I personally use a Levin tube is to prevent this ileus from becoming so pronounced that it will cause complications on its own.”
*708Despite plaintiff’s argument to the contrary, the sequence of events here does not point to the solid food as a probable cause of the subsequent complications. There is no evidence to show when the meso-colon separated, and ten days elapsed between the two operations. During that period plaintiff consumed not only the solid food but also the liquid diet. It does not appear that the solid food put any more weight on the anastomosis than did the liquid diet, and Dr. Rainone was not asked whether it is more likely that one rather than the other caused the separation of the meso-colon. The evidence does not disclose whether the gas pains and other discomfort experienced by plaintiff on and. for several days after August 12 were unusual or normal. During the ten-day period between the two operations, moreover, plaintiff was out of bed, sitting up and moving around. In accordance with Dr. Rainone’s instructions, he sat on the edge of the bed, coughed and turned over in bed at regular intervals during the first two days following the initial operation. One of the forces suggested as a possible cause of his later difficulties was thus operating even before the solid food was eaten and for several days thereafter.
There are other circumstances that should be noticed. Dr. Rainone directed that two precautions be taken for the purpose of avoiding a number of complications. One of his orders was disregarded, and this was followed by separation of the meso-colon, one of the complications he wished to prevent. The evidence also indicates that the failure to observe his instructions with respect to food made the other precaution, i.e. the Levin tube, less effective than it otherwise would have been. On the other hand Dr. Rainone, who was familiar with all the facts, stated positively that there are three possible causes of the separation and that it is just as reasonable that one thing could have caused it as another. In view of this undisputed testimony by plaintiff’s witness, it is our opinion that the circumstances mentioned do not establish a traceable chain of causation from the separation back to the solid food.
This is not a case in which general experience and common sense afford a reasonable basis for concluding that the two meals consumed by plaintiff on August 12 probably caused or contributed to his subsequent difficulties. The evidence does not disclose with what frequency surgical unions give way when the surgeon’s instructions are observed in every respect after an operation similar to that performed on plaintiff. We are not told to what extent, if any, the solid food increased the danger that the stitches would simply fail to hold or be torn loose by the operation of other forces. Since the jury could only speculate as to whether the meso-colon would have separated if plaintiff had not been served the two meals, the trial court did not err in instructing a verdict for defendants.
The judgment of the Court of Civil Appeals is affirmed.
Dissenting opinion by POPE, J., joined by SMITH and McGEE, JJ.