Kidney stones are hard substances formed in the kidneys by some components of urine, small as grains and larger than pearls. Kidney is the most common site of urinary calculi. Most of the kidney stones do not need medical treatment. They can be discharged by themselves without discomfort or slight pain. But some stones are difficult to discharge, even stuck in the ureter, resulting in obstruction of urine outflow, causing severe pain and even bleeding. Kidney stones are the most common type of urinary calculi. If there are no symptoms now, it is recommended that you drink more water and follow up.