Malignant ureteral obstruction: preliminary results of treatment with metallic self-expandable stents.

Self-expandable metal stents 7 mm in diameter were percutaneously implanted into 13 ureters in 10 patients with malignant ureteral obstruction not amenable to double-J stent placement. In nine ureters, one stent was placed, and in four ureters, two overlapping stents were placed. Primary reconstitution of ureteral patency was achieved in all ureters. After 1-2 weeks, four ureters showed a urothelial reaction encroaching on the lumen of the ureter, and a double-J stent was placed coaxially. One ureter was occluded by urothelial hyperplasia 4 weeks after stent placement, and a double-J stent was therefore placed. One ureter was occluded 8 months after stent placement by distal tumor overgrowth. The other ureters showed no signs of obstruction during a follow-up of 3-14 (average, 5.8) months. Peristalsis was preserved at both ends of the stent in all ureters. The use of this stent alone or in combination with a double-J stent alleviated upper urinary tract obstruction and avoided external drainage in all patients.