I would add however, that some STIs are more easily transmitted than others. Of all STIs I would worry about this in, the major concern, I think, would probably be trichamonas. EWH
I understand the concern but again would suggest that this is analgous to the situation in which a male's urethra might be exposed to genital secretions during frottage. While not specifically studied, we don't see infection due to this. I would not worry. EWH
Thank you Dortor Hook, but what about vaginal fluids entering (in the supposed case) the other woman's urethra or any other opening?
Welcome to our Forum and thanks for your question. I was not familiar with the term tribadism for scissoring. While there is no research that I am aware of on the subject, I would think that tribadism should be considered a form of frottage (non penetrative genital rubbing) and such activity however is not a risk for HIV or any other STI. In frottage, since friction is part of the activity by design, chaffing and irritation is common, yet again, there is no risk for HIV.
I would not worry about HIV risk from tribadism and see no need for HIV testing related to the process. I hope my comments are helpful. EWH