If Sally-Sue's parents walked up to Elder Marvin and said: 'Hey! Brother Phaux raped my Sally! Here, look at her! HER ANUS IS BRUISED!!!' What would the Elder do?
I don't think this would be appropiate. But maybe if the parents took Sally to her doctor and he made note of that physical evidence, then the elders could use it against the abuser.
Physical abuse is taken into consideration. For example, there was a case of a physical beating my a parent to their child. A family member spoke to an elder and told him that the child had been beaten heavily. The elder told the family member to bring him the child so that he could see the marks on his body, that way there were two witnesses to the bruises, the elder and the family member. After that the the father was confronted by the elder, and although the father minimized the incident, the elder said that he had seen the bruises on the childs back and legs and they were not minor.
After calling the Legal Department, the case was reported to child protection services. They sent out a social worker to visit the whole family.
So, as you see, in this case, physical evidence was taken into consideration and used when interrogating the father.
With regards to your example, we have to remember that the child that was abused has gone through enough. Why would you subject her to so much humiliation as you recommend? It's better for a doctor to examine her, as I mentioned before.