They can block the flow of urine and cause severe pain. If they scratch the bladder wall, they may lead to an infection or bleeding. Blood may be visible or in trace amounts that only a test can detect. The causes of bladder stones are not completely understood. Diet and fluid intake appear to be important factors.
Stones seem to be more common in hot climates and during summer months.
They are more common in the southeast and southwest regions of the United States. This may be because hot weather leads to body fluid loss. It may also be due to regional diet. Stones are more common in men and rare in children and African Americans. People with gout can have stones made of uric acid.