25 y.O. Female routine pap smear found microscopic hematuria. No pain, no symptoms, and nurse says no infection. What could be the cause?

Two different source. Microscopic hematuria describes that blood was found in the urine from the bladder. A routine pap smear tests the cervical cells found inside the vagina. The test and the results seem to be from two different sources. You should call your nurse and ask her to clarify the findings as well as the next step.
A U/A, not. A pap will show microscopic heamturia. I'd first repeat it, and make sue it is not done at thetime you were instrumnted for the pap, and not close to your menses. It can be an infection, irritation of bladder or urethra, and upper tract (kidney or ureter, and cancers if you are over 40.