A stone impacted in the urethra usually needs at least three days to pass spontaneously. If it cannot move, fragmentation is required; the exact clearance time varies from person to person. The urethra has three natural narrow points. A stone that is too large becomes impacted, causing obstruction and local inflammatory edema. Copious fluid intake is encouraged to drive the calculus downward. Once the stone starts to migrate, complete expulsion usually occurs within about 72 h. For stones that fail to move: Extracorporeal shock-wave lithotripsy (ESWL) is performed; afterward, most fragments pass with increased hydration. If ESWL is unsuccessful, holmium-laser... Learn more