The presence of enlarged kidneys with multiple cysts in a young adult patient complaining of bilateral flank pain and hematuria should raise the possibility of an autosomal dominant polycystic kidney disease (or "adult polycystic kidney disease"). Especially because the patient was considered previously well, with no history of renal diseases, and her kidneys are still demonstrating a preserved cortex. 

The images haven't shown any complicated cyst that catches the radiologist's attention.