It won't work as a dilator, because it's not going to extend all along the length of the vaginal canal. It *probably* isn't a great idea to collect the blood either, because (unlike in menstruation) the blood is coming from the whole vaginal walls and not from the cervix (which the cup fits over and trans women don't have as such...). Not to mention that, again unlike menstruation, this is blood mixed with tissue and other surgical shedding, and is part of a healing surgical site - I'd be seriously worried about infection.