Bladder stones can occur when urine remains in the bladder after urination. Minerals are present in urine, and when urine isn't expelled, those minerals can crystallize inside the bladder, forming bladder stones. Other causes of bladder stones include bladder inflammation, urinary tract infections, and kidney stones. Conditions such as neurogenic bladder, bladder diverticula, or enlarged prostrate can contribute to bladder stones. The use of medical devices, such as a bladder catheter, can also cause bladder stones to form.