Appeal by the defendant from a judgment of the Supreme Court, Kings County (Zweibel, J.), rendered April 6, 1990, convicting him of rape in the first degree, sexual abuse in the first degree (three counts), and assault in the second degree, upon a jury verdict, and imposing sentence.
Ordered that the judgment is affirmed.
At trial Detective Francis Harten, a serologist qualified as an expert, testified that there were several reasons why the victim’s gynecological exam, performed after the rape, may have produced negative results regarding the presence of sperm. On appeal the defendant argues that this testimony was speculative and improperly bolstered the complaining witness’s allegations of rape. We note that at trial, defense counsel registered an unelaborated, general objection after the witness had already provided a few reasons for the existence of negative test results. This objection was inadequate to preserve the issue for appellate review (see, People v Balls, 69 NY2d 641). In any event, the contention has no merit. Although the detective’s testimony was not conclusive on the subject of the negative test results, each of the reasons he gave for explaining those results signified a probability supported by a rational basis. Therefore the expert testimony was not speculative as the defendant claims (see, e.g., People v Bethune, 105 AD2d 262). Furthermore, since the detective testified that one possible explanation for these results was that the victim was not raped, his testimony, contrary to the defendant’s assertion, did not improperly bolster the victim’s *658allegations. Thompson, J. P., Harwood, Rosenblatt and Miller, JJ., concur.