Is a good example of 'intestinal fortitude' when someone faces his/her fair share of adversity and bounces back from it? Or when a boxer is repeatedly pummeled and knocked down in a fight, and he keeps returning to his feet to continue notwithstanding the beating endured (he's showing a lot of heart, internal strength and 'guts')? Can you say 'He had the intestinal fortitude ('guts') to call me a buffoon'? Is 'ovariological fortitude' the female equivalent of this term?
Intestinal fortitude is merely a mock-sophisticated synonym for guts meaning “tenacious strength or courage,” popular among sports commentators. You can use the two terms interchangeably, although intestinal fortitude may come across as affected or pretentious.
Guts isn't a gendered term, so I'm not sure why you'd want a feminine version of it, and I would not expect people to infer guts from your proposed alternative.