Extracorporeal shock wave lithotripsy and stents: fluoroscopic observations and a hypothesis on the mechanisms of stent function.

Fluoroscopic observations made during voiding cystography on 5 patients suggest that a possible reason that double-J ureteric stents are effective in the management of steinstrasse after extracorporeal shock wave lithotripsy (ESWL) is because they allow free fluid reflux from the bladder to the kidney. This reflux in turn triggers active peristalsis down the ureter. These observations may help us in understanding the function of ureteric stents, and suggest that stents should only have side holes at their proximal and distal ends; no side holes should be present along the shaft of the stent. Stone fragments are propelled down the ureter around the stent, hence narrow stents are preferred.