Urothelial hyperplasia complicating use of metal stents in malignant ureteral obstruction.

Self-expandable metal stents (7 mm in diameter) combined with coaxial double-j stents were placed in 10 ureters in ten patients with malignant ureteral obstruction. After 2 and 3 months, when the double-j stents were removed in seven patients, six patients developed hydronephrosis and one patient tolerated removal of the double-j stent and had no signs of urinary obstruction until she died in the fifth month. A double-j stent was inserted again in six patients who developed hydronephrosis. Endoscopy performed during insertion of the double-j stents showed urothelial hyperplasia and incrustations which reduced the lumen of the metal stent. Their double-j stents were exchanged with new ones every 3 months. In the last three patients, double-j stents were not removed, but exchanged with new ones every 3 months. Endoscopy performed regularly during the exchange of the double-j stents in the follow-up of nine patients showed that urothelial hyperplasia, although mild, persisted until the sixth month in three patients. We conclude that urothelial hyperplasia and incrustations limit the use of metal stents in malignant ureteral obstruction. Metal stents, however, when used together with the coaxially placed double-j stents, contributed to the achievement of internal urinary drainage in this study. Since a metal stent provides a buttress for the previously obstructed segment of the ureter, the lumen, although decreased by hyperplasia and incrustations, is held open, which allows an easy exchange of the double-j stent. Regarding the high cost of metal stent, use of it with a coaxial double-j stent should be spared for the malignant ureteral obstructions when a previously placed double-j stent alone fails to achieve efficient drainage.