Not to shore up her story, but Nifong and the Durham PD knew that the Duke medical report would not support the sensational allegations she was making. Miraculously, she appears at the UNC Hospital the next day (we don't know what they said, other than Crystal telling them even different stories about what happened).
True, we don't know what UNC Medical said, but it seems to me that if their findings supported the rape allegation, Nifong would have been hooraying about two different medical findings consistent with rape instead of just the one from Duke.