In this rape prosecution the defense was consent. A psychiatrist, called by the State in its rebuttal case, testified that the victim suffered from post-traumatic stress disorder (PTSD) and that in his opinion, based on the history furnished to him, the cause of the disorder was the rape complained of by the victim. The Court of Special Appeals reversed, concluding that the probative value of the evidence was outweighed by unfair prejudice. Allewalt v. State, 61 Md.App. 503, 487 A.2d 664 (1985). This Court granted cross-petitions for certiorari. For reasons hereinafter stated, we shall reinstate the judgment of conviction.
The incident in question occurred in the early morning hours of Saturday, June 25, 1983, in the victim’s home. The defendant, William Alfred Allewalt (Allewalt), a six-foot, 160-pound, twenty-year-old, was employed as a tire changer. The prosecutrix, Mrs. Mary Lemon (Lemon), age thirty-six, five-feet-eight-inches, 138-pounds, worked as a beautician. Allewalt was the live-in boyfriend of Mrs. Lemon’s eighteen-year-old daughter, Charlene. When Charlene was fifteen she had become pregnant by Allewalt and had had an abortion. Unknown to Allewalt at the time of the incident, Charlene was again pregnant by him. The household occupied a two-story townhouse. Mrs. Lemon, who was separated from her husband, used the master bedroom on the second floor; Charlene and Allewalt occupied a bedroom in the basement; another daughter, Evonne, age fourteen, had a small bedroom on the second floor; two toy poodles owned by Mrs. Lemon slept in her bedroom; and a Doberman pinscher puppy, a gift from Allewalt to Charlene, lived in the basement. Habitually, the older of those poodles would attempt to bite Allewalt in the legs.
Around midday of Friday, June 24, Charlene and Allewalt had quarreled at the Lemon home. Charlene and Evonne spent the balance of Friday visiting at their aunt’s house, where they stayed overnight. Allewalt and a male friend spent Friday evening drinking in various bars and Allewalt *92estimated that he consumed fifteen to twenty bottles of beer that night. Mrs. Lemon spent the evening at home, watching television in her bedroom, and retired about 11:00 p.m.
Allewalt, intoxicated, returned to the Lemon residence at about 3:00 a.m. When he noticed that the puppy had been left unattended, he went to Mrs. Lemon’s bedroom door, knocked, and awakened her. They conversed briefly in the doorway about the puppy and about when Charlene would return. What happened next was the subject of conflicting evidence.
Mrs. Lemon testified that Allewalt then forced his way into her bedroom. She told him not to do what he was thinking. There was a struggle and Mrs. Lemon’s back struck the jam of the bedroom door. Allewalt, reaching around Mrs. Lemon from the rear, seized her by the arms, picked her up, and carried her from her bedroom, where her poodles were left confined, down the hall to Evonne’s bedroom. In the course of a struggle in the hall, a framed picture was knocked from the wall and the glass shattered on the floor. Allewalt threw Mrs. Lemon on Evonne’s bed and raped her. After Allewalt left the room and Mrs. Lemon no longer heard him moving in the house, she went next door to her neighbors, James and Patricia Bailey.
Allewalt testified that the conversation ended in the hall, after Mrs. Lemon had closed her bedroom door from the outside because her poodles were barking. He said that she turned off the hall light by a switch next to her bedroom door and in the darkness put her arm around his waist. He put his arm around her waist and the two, side by side, went down the hall to Evonne’s bedroom. His staggering caused them to brush against the picture which was knocked from the wall. They fell across the bed. Without any conversation, but with Allewalt reading Mrs. Lemon’s “body language,” they engaged in sexual intercourse. After penetration and ejaculation Mrs. Lemon pushed against Allewalt’s chest and told him to stop. He returned to the *93basement where he slept briefly. When he was awakened by the poodles barking, he briefly looked for Mrs. Lemon and then spent the balance of the night at the home of his drinking companion. Allewalt returned to the unoccupied Lemon home shortly after daylight Saturday morning, showered, dressed, and went to work. He had a discussion with his employer who telephoned the police and learned that Allewalt was accused of rape. Allewalt waited for an officer to come to make the arrest.
The neighbor, James Bailey, testified that early in the morning of Saturday, June 25, he heard through the common wall Allewalt saying, “Come on. Come on,” and that he heard Mrs. Lemon yell, “Help me. Help me. Stop.” Mr. and Mrs. Bailey each described Mrs. Lemon, when she came to their house, as hysterical, with red marks on her wrists and the seam of her robe torn at the shoulder. The first police officers to arrive described Mrs. Lemon as very upset, almost incoherent, nearly hysterical, crying, with raw, reddish marks on her arms. A physician who examined Mrs. Lemon at a hospital at approximately 6:00 a.m. described her as quietly sobbing. That doctor found faint bruises on Mrs. Lemon’s back and purple bruises on both elbows.
Prior to the State’s rebuttal case the circuit court conducted a hearing out of the presence of the jury in order to decide whether to admit into evidence certain opinion testimony from Dr. Michael Spodak, a forensic psychiatrist, concerning PTSD. At the conclusion of the questioning defense counsel objected on the ground that the jury did not need help from an expert in deciding so basic an issue as consent and on the further ground that under the Frye-Reed test PTSD induced by rape “has not been recognized in the State of Maryland as being generally accepted within the scientific community____” 1 The court ruled that PTSD “has been around for a long time,” is “nothing new,” and is *94“recognized.” The court thought Dr. Spodak “will be able to assist that jury in making a determination as to [Mrs. Lemon’s] state of mind at the time of the event on the basis of post event findings.”
The State then recalled Mrs. Lemon. She testified that following June 25, 1983, her nerves got worse, she cried all the time and could not eat. When she closed her eyes or tried to sleep, she could see Allewalt standing in the doorway of her bedroom dressed as he was on the night of the occurrence. Following that night she has been wondering if neighbors, friends, and acquaintances thought she was “cheap,” or if she was “dressing cheap,” or if they were looking at her out of their windows when she came out of her home. She was uncomfortable around young males and particularly when she was alone with a young man with whom Charlene had begun keeping company.2 Generally Mrs. Lemon would not leave the house other than to go to work. Cross-examination developed that in March of 1983 Mrs. Lemon had begun receiving treatment for depression once a week at a mental health clinic and had been taking an anti-depressant, amitriptyline, as well as valium. Prior to June 25 her nerves were “bad” and she occasionally had crying spells.
Dr. Spodak explained to the jury that PTSD “is a condition recognized in psychiatry as the emotional reaction to a traumatic event.” The characteristics of PTSD include: insomnia, exaggerated startle response, feelings of guilt, loss of appetite and of weight, avoidance of reminders of the traumatic event, and a sense of fearfulness, A person with PTSD can also experience nightmares and flashbacks, usually relating to the traumatic event. Dr. Spodak explained that the condition has been identified as long ago as *95the turn of the century but that the terminology has varied. In World War I it was called “shell shock,” later “gross stress reaction,” and in the most recent psychiatric manual, DSM III, the condition is labeled post-traumatic stress disorder.3 PTSD can be caused by physical trauma such as an automobile accident or rape or by emotional trauma without specific physical injury.
Dr. Spodak had examined Mrs. Lemon on October 13, 1983, at the request of the State in order to testify at the rape trial. He conducted a standard psychiatric examination which included taking a psychiatric history, making observations in a mental status examination, obtaining some psychological tests, and reviewing the police report and a medical examination report. In Dr. Spodak’s opinion Mrs. Lemon suffered the mental disorder of PTSD after June 25, 1983. That opinion was based “for the most part” on the history which she reported to him. Dr. Spodak was asked by the State, “[Bjased on what she told you, what would be the trauma that forms the basis for your opinion?” He replied that “[t]he only trauma that she claims that she went through at that time was being raped.” The witness explained that while Mrs. Lemon had undergone some depression and lost some weight as a result of her marital difficulties she was “adjusting to that whole experience when the second trauma occurred in June. After that, she definitely took an emotional nosedive____” When asked if the break up of Mrs. Lemon’s marriage of sixteen years would “be considered a traumatic event such that it would give rise to” the diagnosis, Dr. Spodak replied:
No. First of all, it is not the type of trauma that gives rise to this diagnosis at all. It is more of a stressful situation that can cause a stress reaction with depression and anxiety and so on, but it doesn’t cause nightmares and flashbacks and [avoidance] behavior and being uncomfortable around young males and so on. So, for *96starters, it just doesn’t account for this kind of reaction, and it certainly would be most unusual, if it were to occur at all, to occur three months down the road. If it was going to occur, you would expect it right after the incident. But, as I say, it doesn’t cause this kind of reaction at all.
On cross-examination the witness acknowledged that “almost any trauma” could cause the condition. The trauma need not be life threatening. He knew of one case where the patient’s unjustified arrest for shoplifting had precipitated PTSD. He reiterated that a slow break up of a marriage would not produce the disorder. It requires a direct, sudden shock like coming home and finding the furniture gone or finding one’s spouse in bed with someone else. Defense counsel also asked if the examining psychiatrist would have to believe that a traumatic event took place. Dr. Spodak answered:
A I think it is more important that the individual reporting, that is the patient or person you are evaluating, believes that it took place. But, yes, I think, the whole diagnosis is predicated on the assumption that some traumatic incident occurred, sure.
Q So the diagnosis essentially is predicated on a belief in what the patient indicates to you took place?
A Well, it is that coupled with, because we are constantly called upon to answer the question of whether, especially in work related incidents of trauma, are people malingering or not. If they describe the things that are well recognized in the textbooks as going with the condition and describe the time sequence which matches what is known about the condition, and in this case it is pretty solid evidence that they are giving you the straight scoop, if you will. So, yes, it is true that one has to presume that the trauma actually occurred. But there are a lot of other ways of in a sense checking out a story that has to do with what is known about the condition.
*97The jury found Allewalt guilty of second-degree rape, common law assault, and sexual offense in the fourth degree. The court imposed concurrent sentences of ten years imprisonment, with five years suspended, for the rape conviction and of eighteen months imprisonment for each of the other two offenses.
The Court of Special Appeals recognized that evidence of PTSD “is relevant and material insofar as any information tending to support an inference of consent or lack of consent affects the ultimate determination of whether a rape occurred.” 61 Md.App. at 514, 487 A.2d at 669. Nevertheless the court concluded that “[djespite the satisfaction of these requirements, PTSD testimony remains inadmissible because of the prejudicial impact it has on a rape case.” Id. The court said that the diagnosis “does not reliably prove that a victim did not consent to sexual intercourse, but only indicates that the victim displays certain symptoms.” Id. The court pointed out that “[wjhile evidence of PTSD may be relevant to prove the victim’s resulting injury, it does not establish that rape was the trauma causing it.” (Footnote omitted). Consequently, said the court, the “diagnosis has little probative value” on the issue of “whether a rape caused the disorder.” Id. at 515-16, 487 A.2d at 670. This “limited” probative value was held to be outweighed by prejudice.
The court explained the prejudice to be that
expert testimony regarding PTSD unduly corroborates the victim’s rendition of the incident. By stating that a rape could cause the disorder, an expert implicitly verifies the victim’s claim that the rape did cause it. This leads to confusion as to the issue being decided and creates the perception that no further factfinding is necessary. See, State v. Taylor, [663 S.W.2d 235 (Mo.1984) ]; State v. Saldana, [324 N.W.2d 227 (Minn.1982) ]; State v. McGee, [324 N.W.2d 232 (Minn.1982)]. [Id. at 516, 487 A.2d at 670 (italics in original).]
The court concluded *98the evidence proves only the result of a trauma, and does not conclusively establish the type of trauma. Hence, the introduction of PTSD into evidence constitutes reversible error. [Id. (emphasis added).]
I
The analysis by the Court of Special Appeals erects an unreasonably high standard for the admissibility of medical opinion evidence. The analysis also mischaracterizes the evidence in this case as if the medical opinion had been presented as a scientific test the results of which were controlled by inexorable, physical laws. Further, the analysis ignores Dr. Spodak’s opinion that, based on the history, the stressor causing PTSD in Mrs. Lemon following June 25, 1983, was what she said was a rape occurring on that day.
The basic admissibility of Dr. Spodak’s testimony is controlled by Beahm v. Shortall, 279 Md. 321, 368 A.2d 1005 (1977). There we overruled Parker v. State, 189 Md. 244, 55 A.2d 784 (1947). Under Parker the admissibility of medical opinions based upon the patient’s narrative of subjective complaints had been limited to opinions rendered by attending physicians thereby excluding the opinions of physicians engaged only to testify, as was Dr. Spodak in this case. Beahm permits the physician who examined a patient in order to qualify as an expert witness to present his medical conclusions and the information, including history and subjective symptoms, received from the patient which provide the basis for the conclusions.4 Dr. Spodak’s opinion that *99the PTSD which he diagnosed in Mrs. Lemon was caused by the rape which she described is as evidentiarily reliable as an opinion by an orthopedist who has been engaged only to testify ascribing a plaintiffs subjective complaints of low back pain to soft tissue injury resulting from an automobile accident described in the history given by the plaintiff. Maryland evidence law recognizes such medical opinions to be competent on, and relevant to, the issue of causation in addition to the fact of bodily harm.5
There is no issue in this case over the fact that psychiatrists and psychologists recognize PTSD as an anxiety disorder. It is diagnostic category 309.81 in DSM III. Its “essential feature is the development of characteristic symptoms following a psychologically traumatic event that is generally outside the range of usual human experience.” Id. at 236.
The stressor producing this syndrome would evoke significant symptoms of distress in most people, and is generally outside the range of such common experiences as simple bereavement, chronic illness, business losses, or *100marital conflict. The trauma may be experienced alone (rape or assault) or in the company of groups of people (military combat). [M]
DSM III, at 238, presents four categories of diagnostic criteria for PTSD, the first of which is the “[existence of a recognizable stressor that would evoke significant symptoms of distress in almost everyone.” 6 Consequently, Dr. Spodak was acting well within the field of his special training and experience not only when he made the diagnosis but, since the diagnosis requires identifying the “recognizable stressor,” when he opined that the trauma was the rape described by the patient.
*101Read literally, the opinion by the Court of Special Appeals would require Dr. Spodak’s opinion to “establish” that a rape had occurred and indeed, to establish that fact “conclusively.” A slavish application of so rigid a requirement would eliminate most of the evidence at trials of all kinds. We said in Dorsey v. State, 276 Md. 638, 643, 350 A.2d 665, 668-69 (1976) that
[t]he real test of admissibility of evidence in a criminal case is “the connection of the fact proved with the offense charged, as evidence which has a natural tendency to establish the fact at issue.” MacEwen v. State, 194 Md. 492, 501, 71 A.2d 464, 468 (1950); Pearson v. State, 182 Md. 1, 13, 31 A.2d 624, 629 (1943). In Kennedy v. Crouch, 191 Md. 580, 585, 62 A.2d 582, 585 (1948), our predecessors stated it to be “an elementary rule that evidence, to be admissible, must be relevant to the issues and must tend either to establish or disprove them.” [Emphasis added.]
The determination of the relevance of specific evidence within the circumstances of a given case rests with the discretion of the trial court. Johnson v. State, 303 Md. 487, 527, 495 A.2d 1, 21 (1985). Where the proffered evidence is competent opinion testimony, the trial court must also determine, in its discretion, whether the opinion and reasons for it will aid the trier of fact. Consolidated Mechanical Contractors, Inc. v. Ball, 263 Md. 328, 338, 283 A.2d 154, 159 (1971). Here the trial judge concluded that Dr. Spodak’s diagnosis of PTSD, coupled with his opinion on the cause of that disorder, would aid the jury. We have said “that the causes of emotional disturbances are complicated medical questions, proof of which must be made by expert medical testimony.” Johnson v. Zerivitz, 234 Md. 113, 116, 198 A.2d 254, 255 (1964). And compare Board of Trustees v. Rollins, 269 Md. 722, 309 A.2d 758 (1973) (payment of special disability benefits properly ordered where medical opinion finding functional overlay was uncontradicted) with Wilhelm v. State Traffic Safety Commission, 230 Md. 91, 101, 185 A.2d 715, 719 (1962) (absent expert testimony, the *102issue of the causes of the plaintiffs emotional disturbances properly withheld from jury).
The Court of Special Appeals nevertheless held that the trial judge had abused his discretion in admitting the expert testimony because prejudice was said to outweigh the probative value of Dr. Spodak’s opinion. The finding of overriding prejudice rested on the assumption that the jury would be confused and might conclude that, because rape was one of the possible causes of PTSD, it had in fact caused the disorder found in Mrs. Lemon. As we have set forth, supra, Dr. Spodak not only gave his diagnosis and identified the described rape as the cause of the disorder but he also explained his opinion on causation by reference to the history obtained from Mrs. Lemon and by excluding other possible causes. Prejudice in the evidentiary sense which can outweigh probative value involves more than damage to the opponent’s cause. See McCormick on Evidence § 185, at 545 (3d ed. 1984).
All evidence introduced against a defendant, if material to an issue in the case, tends to prove guilt, but is not necessarily prejudicial in any sense that matters to the rule of evidence____ Evidence is prejudicial only when it tends to have some adverse effect upon a defendant beyond tending to prove the fact or issue that justified its admission into evidence____ The prejudicial effect may be created by the tendency of the evidence to prove some adverse fact not properly in issue or unfairly to excite emotions against the defendant. [United States v. Figueroa, 618 F.2d 934, 943 (2d Cir.1980).]
We find nothing in the record now before us which justifies the Court of Special Appeals’ apparent concern that Dr. Spodak was presenting a kind of mystical infallibility. He did not purport to have invented a scientific test for determining consent to sexual intercourse had months earlier. He did claim that he could use his special knowledge and the interviewing techniques of his profession to diagnose whether Mrs. Lemon, at the time of his examination of her, suffered from a medically recognized anxiety disorder. *103He did not claim that psychiatry could demonstrate conclusively that the cause of the PTSD was rape. He did claim the special knowledge and experience to be able to identify the cause of the PTSD by utilizing the history furnished by the patient, a utilization permitted under our holding in Beahm, supra, 279 Md. 321, 368 A.2d 1005. Having heard the evidence the jury still had to evaluate the credibility of Mrs. Lemon and of Dr. Spodak, and to evaluate what weight, if any, they would give to his opinion. Indeed the trial judge instructed the jury that it “should give experts’ testimony the weight and value you believe it should have. You are not required to accept any expert’s opinion.”
By holding on the present record that the trial court abused its discretion the Court of Special Appeals has in effect excluded PTSD evidence as a matter of law in every rape case in which consent is the ultimate issue. The court cited decisions of the supreme courts of Minnesota and Missouri in support of the holding of overriding prejudice. Allewalt, in his brief to this Court, also puts the question presented in absolute terms by further contending that PTSD evidence is not accepted in the relevant scientific community “as a reliable means of identifying the underlying trauma.” Phrased in that form Allewalt’s argument simply erects a strawman. That argument is like saying a medical diagnosis of a broken bone is not accepted in the relevant scientific community as a reliable means of identifying the underlying trauma (or disease) which caused the break. The appropriate inquiry in the present case is whether there is some policy applicable to evidence offered in rebuttal of consent in a rape case which prevents a qualified psychiatric witness from expressing an opinion, based on the patient’s history, as to the cause of a recognized disorder, PTSD, from which, in the expert’s opinion, the patient suffers.
The cases relied upon by the Court of Special Appeals and by Allewalt dealt with testimony about “rape trauma syndrome” (RTS). The quoted expression had its origin in an article by Burgess & Holmstrom, Rape Trauma Syn*104drome, 131 AmJ.Psychiatry 981 (1974) in which the authors reported on a study of those patients admitted during a one-year period to the emergency department of Boston City Hospital who presented a complaint of having been raped. RTS is the terminology used by some for a PTSD subset in which the trauma is rape. Consequently one of the diagnostic criteria of PTSD, namely that the trauma be reexperienced, would in such cases involve a reexperiencing of the sexual assault.
In State v. Saldana, 324 N.W.2d 227 (Minn.1982), the expert witness was the director of a victim assistance program who held a bachelor’s degree in psychology and social work. The witness “explained the stages that a rape victim typically goes through and discussed typical behavior of victims after a rape.” Id. at 229. The witness “stated that [the complainant] was the victim of ‘acquaintance rape,’ that [the witness] definitely believed [the complainant] was a victim of sexual assault and rape, and that she did not think [the complainant] fantasized or ‘made it up.’ ” Id. The court analogized to its earlier rejection of “battering parent syndrome” evidence, in that “scientific evaluation of rape trauma syndrome has not reached a level of reliability that surpasses the quality of common sense evaluation present in jury deliberations.” Id. at 230. In the court’s opinion “[p]ermitting a person in the role of an expert to suggest that because the complainant exhibits some of the symptoms of rape trauma syndrome, the complainant was therefore raped, unfairly prejudices the appellant by creating an aura of special reliability and trustworthiness.” Id.
A companion case, State v. McGee, 324 N.W.2d 232 (Minn. 1982), held to be inadmissible, for the reasons set forth in Saldana, a physician’s testimony that the complainant’s symptoms were consistent with RTS. In a later sexual assault case the Supreme Court of Minnesota approved the admission of evidence concerning the complainant’s physical and emotional condition shortly after the incident because that evidence tended to corroborate the victim’s testimony. *105The court distinguished McGee and Saldana as cases which “dealt with admission of expert testimony of rape trauma syndrome to establish that a rape occurred.” State v. Booker, 348 N.W.2d 753, 755 (Minn.1984).
The Supreme Court of Missouri has also held that RTS evidence is not admissible. State v. Taylor, 663 S.W.2d 235 (Mo.1984). There the witness, a psychiatrist, had examined the complainant about three months after the assault. He explained RTS to the jury and testified that identifiable symptoms of RTS develop in nearly ninety-five percent of all rape and sexual assault victims. He opined that the complainant suffered from RTS brought on by the rape incident which she described to him. He further testified that the victim “was not fantasizing when she described the rape____” Id. at 237. The court held that the psychiatrist’s
statements that the prosecutrix suffered from rape trauma syndrome and that she had been raped are not sufficiently based on a scientific technique, which is either parochially accepted or rationally sound, to overcome the inherent danger of prejudice created by his status as an expert.
There are inherent implications from the use of the term “rape trauma syndrome”, for it suggests that the syndrome may only be caused by “rape” as the court in Saldana, supra, emphasized. [Id. at 240.]
It was the court’s further view that, inasmuch as the “trauma syndrome could result from a number of stressful situations ... it would be too presumptuous for [the witness] to designate the particular experience.” Id.
The same result was reached by the Supreme Court of California in People v. Bledsoe, 36 Cal.3d 236, 681 P.2d 291, 203 Cal.Rptr. 450 (1984). In that rape prosecution a rape counselor had testified in the state’s case in chief and stated that the complainant suffered from RTS. The court recognized that some courts have allowed evidence on RTS to rebut an inference that the conduct of the complainant was *106inconsistent with a rape by providing the jury recent findings of professional research on the subject of victims’ reactions to sexual assault.7 The court also said RTS evidence could play a useful role in disabusing the jury of widely held misconceptions about rape and rape victims. But in the case before it the court said the RTS testimony was introduced “as a means of proving — from the alleged victim's post-incident trauma — that a rape in the legal sense had, in fact, occurred.” 36 Cal.3d at 248, 681 P.2d at 299, 203 Cal.Rptr. at 458. Unlike a blood test, RTS “was not devised to determine the ‘truth’ or ‘accuracy’ of a particular past event — i.e., whether, in fact, a rape in the legal sense occurred — but rather was developed by professional rape counselors as a therapeutic tool, to help identify, predict and treat emotional problems experienced, by the counselors’ clients or patients.” Id. at 249-50, 681 P.2d at 300, 203 Cal.Rptr. at 459. Because RTS “is not generally recognized or used in the general scientific community from which it arose ... to prove that a rape in fact occurred,” the court held that evidence of RTS could not be used “for that purpose in a criminal trial.” Id. at 251, 681 P.2d at 301, 203 Cal.Rptr. at 460.
At least an equal number of state supreme courts take the opposite view. State v. Marks, 231 Kan. 645, 647 P.2d 1292 (1982) involved the testimony of a psychiatrist from the Menninger Foundation who had examined the complainant two weeks after the alleged rape. Recognizing that “[t]he identification of rape trauma syndrome is a relatively new psychiatric development,” the court nevertheless said that “if the presence of rape trauma syndrome is detectable and reliable as evidence that a forcible assault did take place, it is relevant when a defendant argues the victim *107consented to sexual intercourse.” 231 Kan. at 654, 647 P.2d at 1299. The court then held:
An examination of the literature clearly demonstrates that the so-called “rape trauma syndrome” is generally accepted to be a common reaction to sexual assault. See McCombie, The Rape Crisis Intervention Handbook, pp. 124-26 (1980); Comprehensive Textbook of Psychiatry §§ 21.1d, 24.15, pp. 1519, 1804-05 (Kaplan, Freedman and Sadock 3rd ed. 1980); Warner, Rape & Sexual Assault, pp. 145-49 (1980); Burgess & Holmstrom, Rape: Crisis & Recovery, pp. 35-47 (1979); Katz & Mazur, Understanding the Rape Victim, pp. 215-31 (1979); E. Hilberman, The Rape Victim, p. 36 (1976); Burgess & Holmstrom, Rape: Victims of Crisis, pp. 37-51 (1974). As such, qualified expert psychiatric testimony regarding the existence of rape trauma syndrome is relevant and admissible in a case such as this where the defense is consent. [M8]
The Supreme Court of Montana has agreed with the Kansas court and allows RTS testimony as an aid to the jury. State v. Liddell, 685 P.2d 918 (Mont.1984). Even though rape “is only one such severe trauma which can cause the symptoms,” the court believed “that skilled direct and cross-examination of an expert in this area can assist the jury in determining whether, in fact, the victim consent*108ed to the act.” Id. at 923. Because of its relevance, the court rejected a contention that such evidence would potentially confuse and mislead the jury.
After the California, Minnesota, and Missouri cases had been decided, the Kansas court in State v. McQuillen, 236 Kan. 161, 689 P.2d 822 (1984) again considered the subject. That court saw as the common thread, in the cases where courts have ruled RTS evidence to be inadmissible, testimony from the expert as to “whether or not he believed the victim was telling the truth in stating she was raped by the defendant, thus creating the presumption that she was raped.” Id. at 169-70, 689 P.2d at 828. The Kansas court reaffirmed the position it had taken in Marks, supra.
The Supreme Court of Arizona has recently held that RTS testimony is admissible where the question is one of consent. See State v. Huey, 145 Ariz. 59, 699 P.2d 1290 (1985). The testimony of the expert in that case “centered more on general observations of stress than on a description of a unique psychological response____” Id. at 63, 699 P.2d at 1294. The witness never used the term “rape trauma syndrome,” nor did he describe the two phases of RTS outlined by Burgess and Holmstrom in 131 Am. J. Psychiatry, supra. As an alternative holding the court said that even if the witness had described RTS, the evidence would have been admissible on the rationale of the Kansas and Montana cases.
The salient factors considered in both lines of cases reviewed above lead us to conclude that the trial judge did not abuse his discretion under the circumstances of the instant case. Dr. Spodak never used the term “rape trauma syndrome,” and avoiding that terminology is more than cosmetic. The concern with unfair prejudice is largely reduced when the terminology does not equate the syndrome exclusively with rape. In both his terminology and in his explanation, Dr. Spodak was careful to point out that severe traumas, other than rape, can produce the disorder which warrants the diagnosis of PTSD. Nor did Dr. Spodak *109attempt to express a personal opinion on Mrs. Lemon’s credibility. It was in response to a defense question emphasizing that the validity of the opinion depended on the truth of the history that Dr. Spodak referred, without a motion to strike, to the compatibility of Mrs. Lemon’s description with the textbook symptoms as evidence of what he called getting “the straight scoop.” In addition, Dr. Spodak testified in the State’s rebuttal case after Allewalt had acknowledged having had intercourse with Mrs. Lemon and after he swore it was consensual. Just as a jury can understand that evidence of the complainant’s hysteria shortly following an alleged sexual assault tends to negate consent, so a jury, with the assistance of a competent expert, can understand that a diagnosis of PTSD tends to negate consent where the history, as reviewed by the expert, reflects no other trauma which in the expert’s opinion could produce that medically recognized disorder. By requiring a full explanation on direct, by allowing liberal cross-examination, and by proper jury instructions, all of which occurred in this case, the trial court can prevent any impression that the psychiatric opinion is like a chemical reaction.
We hold only that in this case the trial court did not abuse its discretion in admitting the testimony of Dr. Spodak. We emphasize that admissibility is a matter of trial court discretion based on the facts. When a trial judge admits PTSD evidence because he believes that the existence of the disorder coupled with the absence of any triggering trauma, other than the evidence of rape, will aid the jury the ruling necessarily carries certain baggage with it. Cross-examination can include not only cross-examining the expert about PTSD in general, but also cross-examining the expert and the prosecutrix about possible causes of the disorder other than the assault charged in the criminal case. In addition, we can foresee cases where the defendant will seek to counter the State’s PTSD evidence with his own expert testimony. That can, in turn, lead to issues concerning compulsory psychiatric examination of the complainant by an expert for the defense. Lurking in the background is *110the nice question of whether the absence of PTSD is provable by the accused in defense of a rape charge, as tending to prove that there was consent. See, as to RTS generally, Massaro, Experts, Psychology, Credibility, and Rape: The Rape Trauma Syndrome Issue and its Implications for Expert Psychological Testimony, 69 Minn.L.Rev. 395 (1985); Comment, Expert Testimony on Rape Trauma Syndrome: Admissibility and Effective Use in Criminal Rape Prosecution, 33 Am.U.L.Rev. 417 (1984); Note, Checking the Allure of Increased Conviction Rates: The Admissibility of Expert Testimony on Rape Trauma Syndrome in Criminal Proceedings, 70 Va.L.Rev. 1657 (1984). When ruling on whether to receive State preferred evidence of PTSD a trial judge will have to weigh the benefit of the evidence not only against potential unfair prejudice, but also against the complexity of possibly accompanying issues and against the time required properly to try the expanded case.
II & III
Allewalt presents two additional issues involving sentences which are not permitted by law. On the conviction for fourth-degree sexual offense the court sentenced Allewalt to eighteen months imprisonment, but the maximum imprisonment permitted is one year. See Md.Code (1957, 1982 Repl. Vol.), Art. 27, § 464C(b). On his conviction for common law assault an additional, concurrent sentence of eighteen months was imposed. Allewalt correctly argues that, under the facts of this case, the assault merges into the second-degree rape conviction. See Green v. State, 243 Md. 75, 220 A.2d 131 (1966). Although these issues were not raised in the trial court, they may be considered on appeal. Walczak v. State, 302 Md. 422, 488 A.2d 949 (1985). The State does not contest that these points are substantively meritorious.
JUDGMENT OF THE COURT OF SPECIAL APPEALS VACATED AND CASE REMANDED TO THAT COURT WITH INSTRUCTIONS TO AFFIRM THE JUDGMENT *111OF CONVICTION OF THE CIRCUIT COURT FOR BALTIMORE COUNTY ON THE CHARGE OF RAPE IN THE SECOND DEGREE; TO VACATE THE SENTENCE ON THE CHARGE OF ASSAULT; AND TO REMAND TO THE CIRCUIT COURT FOR BALTIMORE COUNTY FOR RESENTENCING ON THE CHARGE OF FOURTH-DEGREE SEXUAL OFFENSE. COSTS TO BE PAID BY WILLIAM ALFRED ALLEWALT.
. The reference is to Frye v. United States, 293 F. 1013 (D.C.Cir. 1923) and Reed v. State, 283 Md. 374, 391 A.2d 364 (1978).
. By the time of trial in November 1983 Charlene was again living with Allewalt, but at Allewalt's mother’s home. Charlene was a witness called by the defense at the rape trial. Her testimony, contrary to that of Mrs. Lemon, included reference to a lock on the inside of the door of the bathroom off of Mrs. Lemon’s bedroom and to objects in that bathroom which potentially were defensive weapons.
. The reference is to American Psychiatric Assoc., Diagnostic & Statistical Manual of Mental Disorders (3d ed. 1980).
. Under Beahm the conclusions are admissible as substantive evidence, but ‘‘[t]he statements made by the patient, as narrated by the physician, are admissible, with a qualifying charge to the jury, only as an explanation of the basis of the physician’s conclusions and not as proof of the truth of those statements.” 279 Md. at 327, 368 A.2d at 1009 (footnote omitted). The limitation is not a factor here. Mrs. Lemon testified to the significant history. Defense counsel, on cross-examination of Mrs. Lemon, elicited the defense’s competing stressor, i.e., marital separation and resulting depression. Dr. Spodak was present in court, heard Mrs. Lemon’s testimony, and included it as a basis for his opinion. In addition, defense counsel had limited the *99objections to Dr. Spodak's testimony by specifying the grounds for the objection and those grounds had not included hearsay. Finally, no limiting instruction was requested either at the time the evidence was admitted or in the charge to the jury.
. In its Allewalt, the Court of Special Appeals said:
Our exclusion of expert testimony regarding PTSD in criminal cases does not mean that it may not be relevant and material in a civil action for damages. A court could find that such evidence is probative of damages, but we do not decide that issue at this juncture. [61 Md.App. at 515-16 n. 10, 487 A.2d at 670 n. 10.] Cases allowing PTSD evidence to prove the extent of injury in civil
proceedings brought by rape victims include: Redmond v. Baxley, 475 F.Supp. 1111 (E.D.Mich.1979); Division of Corrections v. Wynn, 438 So.2d 446 (Fla.Dist.Ct.App.1983); Alphonso v. Charity Hospital, 413 So.2d 982 (La.Ct.App.1982); White v. Violent Crimes Compensation Board, 76 N.J. 368, 388 A.2d 206 (1978); Skaria v. State, 110 Misc.2d 711, 442 N.Y.S.2d 838 (N.Y.Ct.Cl.1981); Wesley v. Greyhound Lines, Inc., 47 N.C.App. 680, 268 S.E.2d 855 (1980).
Use of a description of PTSD in defense of a civil case is reported in Wilson v. Jackson, 66 Md.App. 744, 505 A.2d 913 (1986).
. The other diagnostic criteria are:
B. Reexperiencing of the trauma as evidenced by at least one of the following:
(1) recurrent and intrusive recollections of the event
(2) recurrent dreams of the event
(3) sudden acting or feeling as if the traumatic event were reoccurring, because of an association with an environmental or ideational stimulus
C. Numbing of responsiveness to or reduced involvement with the external world, beginning some time after the trauma, as shown by at least one of the following:
(1) markedly diminished interest in one or more significant activities
(2) feeling of detachment or estrangement from others
(3) constricted affect
D. At least two of the following symptoms that were not present before the trauma:
(1) hyperalertness or exaggerated startle response
(2) sleep disturbance
(3) guilt about surviving when others have not, or about behavior required for survival
(4) memory impairment or trouble concentrating
(5) avoidance of activities that arouse recollection of the traumatic event
(6) intensification of symptoms by exposure to events that symbolize or resemble the traumatic event[.]
The purpose of stating diagnostic criteria in DSM III was to facilitate communication and research between mental health professionals by "standardizing the classification system with reference to empirically demonstrable phenomena.” Comment, The Psychologist as Expert Witness: Science in the Courtroom?, 38 Md.L.Rev. 539, 580 n. 207 (1979).
. The California court cited as illustrations Delia S. v. Torres, 134 Cal.App.3d 471, 184 Cal.Rptr. 787 (1982) (delay in reporting assault); State v. Middleton, 294 Or. 427, 657 P.2d 1215 (1983) (inconsistent post-incident statements by 14-year-old incest victim); and Terrio v. McDonough, 16 Mass.App. 163, 450 N.E.2d 190 (1983) (complainant returned briefly to scene of attack in order to retrieve belongings).
. A bibliography furnished by Dr. Spodak to the circuit court as a partial listing of authoritative works on the psychological reactions to the trauma of rape includes the following references:
Atkeson, Calhoun, Resick & Ellis, Victims of Rape: Repeated Assessment of Depressive Symptoms, 50 J. Consulting and Clinical Psychology, 96-102 (1982);
Burgess & Holmstrom, Adaptive Strategies and Recovery from Rape, 136 Am.J.Psychiatry, 1278-82 (1979);
Martin, Warfield & Braen, Physician’s Management of the Psychological Aspects of Rape, 249 J.A.M.A., 501-03 (1983);
Norris & Feldman-Summers, Factors Related to the Psychological Impacts of Rape on the Victim, 90 J. Abnormal Psychology, 562-67 (1981); and
Schuker, Psychodynamics and Treatment of Sexual Assault Victims, 7 J.Am.Acad.Psychoanalysis, 553-73 (1979).