Bladder stones are hard masses of minerals that form in the urinary tract and end up in the bladder. They can occur when urine in the bladder is concentrated and materials in urine begin to crystallize. Bladder stones are much less common than kidney stones. Some of the common symptoms are pain in the abdomen, painful urination, frequent urination cloudy or abnormally dark-colored urine and the presence of blood in the urine. Men comprise 95% of the patients with bladder stones. Nobody is sure of the exact cause of bladders stones, although the most common conditions that cause bladder stones include: Prostate gland enlargement, damaged nerves (neurogenic bladder), Inflammation, Medical devices and Kidney stones, Genetic factors can also contribute to bladder stones. Other factors include gout, hormone imbalances, urinary infections, and urinary obstruction.