Kidney stones are not easy to expel from the body, especially those in the lower renal calyces. If a calyx stone is small enough to pass through the neck of the calyx, it may fall into the renal pelvis and drain into the bladder via the ureter and out of the body. If the calyx stone is > the diameter of the calyx neck, the stone cannot be discharged into the renal pelvis. Small stones that are not complicated by fluid retention or infection will not affect kidney function and require regular review and dynamic observation. If the stone is larger, it may form a stone of the calyx cast type, and further increase of the stone may protrude into the pelvis or other calyces from the neck of the calyx, then it is called antler-shaped stone, which will affect the kidney function and also complicate the infection, and only surgical treatment can remove the stone, and the rate of clearing the stone in one operation is less than 50%.