Bladder stones are small deposits of minerals such as calcium and magnesium that crystallize into either round or, rarely, star-shaped material. They are usually caused by chronic dehydration or when the urinary tract becomes inflamed. Occasionally, kidney stones become bladder stones, after having traveled down the ureter.
Sometimes they cause no discomfort, only being found on x-rays when examining for other conditions. When symptoms are present, they usually include severe pain in the lower abdomen and back, difficult or frequent urination, blood in the urine, and fever.
Increased hydration is the usual way to prevent bladder stone formation. Bladder stones are treated using a surgical procedure called a cystolithotomy.