Kidney stones can be painful for a while and then not be painful at all, depending on the location of the stone. If a stone in the kidney blocks the outlet of the renal pelvis, the urine produced by the kidney cannot be discharged and can accumulate in the kidney and cause pain. However, if the stone leaves the obstructed area, the urine in the kidney can be discharged smoothly and the pressure in the kidney drops, resulting in painless symptoms. This condition is most often seen in renal pelvic stones. It is also possible that a kidney stone may enter the ureter and cause different degrees of ureteral blockage in the process of moving down the ureter, which can lead to changes in the size of the pelvic pressure, pain when the pressure increases, and pain relief or no pain when the pressure decreases. It can also be considered a sign of stone drainage and requires ultrasound or CT dynamic monitoring to understand the location of the stone and the extent of fluid accumulation. When the stone is discharged into the bladder or out of the body, the back pain may be completely relieved or disappear.