According to this article, hospitals do there best to have the most possible certainity about the matter, whether she is potentially pregnant, then give her a recommendation based on their tests.
The woman who is a victim of rape has the moral right to prevent the pregnancy for the following reasons: First, the rapist (including his sperm) is an unjust aggressor who has violated the woman’s dignity. Second, rape is an act of force and violence, unlike the conjugal love in marriage whereby both spouses give freely of themselves in an act of unitive and procreative love. Third, the woman is not responsible for the action, and thereby has the right to prevent the pregnancy. (Please note that for these three reasons, this guidance does not violate the Church’ s teaching regarding contraception as expressed in Humanae Vitae, which, because of the free-giving between spouses, stated, "Each and every marriage act must remain open to the transmission of life (no. 11).)
Still, something doesn’t sit right with me, even with the smallest chance that you would abort a living human being, you shouldn’t take that chance. It doesn’t seem pro-life to me in either mentality or practice. Of course the situation is grave and horrible, but still the principles of HV seem to be violated as well.
Also, the framework from HV, I don’t think it should be narrowed to spouses only, because obviously lots of unmarried couples use contraceptives, and they still are under the ban, though they shouldn’t be having sex in the first place.