[Stents in urology]

Ureteral stents are employed in the upper and urethral stents in the lower urinary tract for restitution or maintenance of urinary drainage. Placement of ureteral stents is indicated as an adjuvant measure prior to extracorporal disintegration (ESWL) of large kidney stones to insure urinary drainage and enhance expulsion of fragments and disintegrate. Also, obstruction by very small urinary tract stones that are not treatable by ESWL because they cannot be localized can be relieved by placement of a double-J-stent with immediate elimination of colic. If the cause of urinary tract obstruction is external ureteral compression (retroperitoneal mass), placement of a special tumor stent is one possibility. This, however, has the danger of becoming reobstructed with detritus and blockage of the drainage holes in the stent. In these cases the essential drainage along the stent is blocked by the mass. Therefore, a percutaneous nephrostomy providing direct drainage is easier to control and preferable. Obstructive pyelonephritis is an absolute indication for drainage of the upper urinary tract with a double-J-stent, or even better by percutaneous nephrostomy. If pyeloureteral or ureteral stenoses of the upper urinary tract are opened endoscopically, then the double-J-stent serves to maintain and insure drainage until the new lumen is reepithelialized. In patients with prostatic hyperplasia who no longer respond to medical treatment and who are not candidates for more invasive surgical treatment, a stent can be placed in the prostatic urethra under local anesthesia as a last resort. This procedure is seldom used but, in view of the satisfactory long-term results, it provides a true alternative to bladder drainage by transurethral catheter or percutaneous cystostomy. The same stents may be used in the bulbar urethra to reduce restricture rates following endoscopic treatment of strictures.