Kidney stones, X-ray - Stockfoto

X-ray of the abdomen of a patient showing kidney stones, also known as renal calculi. Kidney stones are usually formed by the precipitation of the mineral salt calcium oxalate from the urine. The resulting hard, round stones (calculi) may cause severe pain, especially as they pass down the urinary tract. Large stones may need to be surgically removed or broken down using ultrasound therapy