The appellants, Va Moua and Xia Fang Moua, were jointly tried on charges of rape, sexual exploitation of a child, and kidnapping with bodily injury. They were found guilty as charged on the rape and sexual exploitation counts but on the kidnapping count were found guilty of the lesser offense of false imprisonment. They bring this appeal from the denial of their motion for new trial. Held:

2. The appellants contend that the trial court erred in allowing the state to present medical opinion testimony on the ultimate issue of whether the victim had consented to the acts of sexual intercourse. The witness in question was a physician who had examined the victim after the incident. He testified that during the course of this examination, he observed lacerations or tears in the victim's perineum which, in his opinion, were consistent with an act of non-consensual sexual intercourse but not consistent with an act of consensual sexual intercourse. "Assuming that such testimony was tantamount to an opinion that the victim did not consent, it was not error to allow such testimony. The doctor was qualified as an expert, and expert opinion testimony on issues to be decided by the jury, even the ultimate issue, is admissible where the conclusion of the expert is one which the jurors would not ordinarily be able to draw for themselves, i.e., the conclusion is beyond the ken of the average layman. [Cit.] Clearly the significance of tears in the [perineum] would be beyond the ken of the average layman. Accordingly, it was not error to allow such testimony." Russell v. State, 181 Ga. App. 624, 626 (353 SE2d 820) (1987). Accord State v. Butler, 256 Ga. 448 (349 SE2d 684) (1986).

3. The appellants contend that in charging the jury on the element of false imprisonment, the trial judge erred in failing to include instructions on their "sole defense" of consent. This contention is without merit. The trial court had previously given a full and correct charge on consent in connection with the charge on rape, and "[u]nder these circumstances, [an additional] charge on consent [as it related to the offense of false imprisonment] would have done nothing more than point out what was already clear from the charges given the jury, i.e., that if the jury believed that there was a reasonable doubt as to whether the [appellants had kept] the victim [in the motel room] against her will, they should not find [them] guilty of [false imprisonment]." Sims v. State, 148 Ga. App. 359, 360 (3) (251 SE2d 380) (1978).

4. The appellants contend that the false imprisonment convictions and the rape convictions should have been merged because they were based on the same conduct. However, a rational trier of fact could reasonably have concluded from the evidence that the confinement and detention of the victim far exceeded that which was immediately associated with the acts of sexual intercourse. Accordingly, this enumeration of error is without merit. Accord Turner v. State, 194 Ga. App. 878, 880 (3) (392 SE2d 256) (1990).