Not sure I understand. Medical examiners can’t prove rape. And the reason for the blood is key. If there is no blood on him then it could be she put it there.
You might do some minor reading if you are going to keep popping off.
If the woman was entered unlubricated, damned straight that can show. If she was entered roughly from awkward angles, that can produce tearing or even permanent damage which doesn't happen even with the BDSM crowd.
Things like that may or may not be present in this case, but they can be and yes - they do prove non-consensual sex.
It might not be able to prove rape, but an examine can show signs of forced or violent sex. That, along with blood found at the scene, makes a pretty strong case.