Transient distal ureteral edema and obstruction have been recognized complications of retrograde ureteral catheterization for years. Similar changes in the proximal ureter may be induced by antegrade (percutaneous) ureteral intubation and are being more widely recognized as radiologists become more involved in upper urinary tract percutaneous manipulative procedures. Marked mucosal edema of the ureter was observed in four patients who had percutaneously placed, in-dwelling stent catheters. This was severe enough to produce transient ureteral obstruction after stent removal in two. Some degree of mucosal edema may be seen in most patients with in-dwelling stents. These ureteral changes may be secondary to the pressure effect of large diameter catheters on the proximal and midureter. Temporary proximal urinary diversion should be maintained until the edematous changes improve or subside, usually within 5-8 days.