See below. When a stone passes out from the kidney it goes into the ureter which is a tube connecting the kidney to the urinary bladder. Depending on the size of the stone, it may either stay in the ureter and cause obstruction (with pain & blood in urine) or passes into the urinary bladder. From the urinary bladder it may eventually pass through the urethra to the outside.
Kidney stone moves. Once the kidney stones passes out of the kidney, it goes into the kidney tube called ureter. It then makes it way all the way down to the bladder and then it is expelled while urinating. During this process, the stone can cause a significant amount of pain and possibly bleeding in the urine.