kidney (renal) stones

Q | do all stones in the urinary tract originate in the kidney?

A | Nobody knows for sure but it is thought that most stones do form in the kidney and colic (pain) occurs when these stones move from the kidney down into the ureter. Bladder stones, however, usually arise within the bladder itself and are probably the result of stagnation of the urine due to bladder outflow obstruction.

This obstruction can be caused by prostatic enlargement (in men) for instance.