Jmrodrig
Your Fiance is does not match the profile of a typical bladder cancer patient. That said, catching BC early is the best key for a good outcome, so a workup is reasonable.
The odds of a female, 29 years young, non-smoker with microscopic blood, and no other identified risks developing bladder cancer is down in the low single digits; but it does happen, rarely. There are LOTS of causes of blood in urine.
Cytology has lots of false positives and false negatives. Atypia is not bladder cancer. A clean CT is a good sign.
Most of us have been through the panic mode the first time we hear the C word and they are talking about us. Ball of stress or freaking out is a mild initial reaction. Lots of people pass through here with a similar story, and most leave after a full work-up either finds a cause or cannot find any cause for a microscopic or occasional small amount of blood in the urine.
She is on the path to an answer. In the worst case, finding bladder cancer EARLY offers the best outcome.
It sounds like you two are on the right track.
Best
Jack