Endopyelotomy for primary ureteropelvic junction obstruction: Risk factors determine the success rate

Purpose: We prospectively assessed the feasibility, complications, and short-term and longterm results of endopyelotomy for primary ureteropelvic junction obstruction. Materials and Methods: In 80 consecutive patients primary ureteropelvic junction obstruction was diagnosed by excretory urogram or nephrostomogram, retrograde pyelography, diuresis renography and the Whitaker test in ambiguous cases. In all patients antegrade endopyelotomy was performed with a cold knife and an indwelling stent was left for 6 weeks. At 6 and 24 months postoperatively results were assessed clinically by an excretory urogram and/or diuretic renography and later by questionnaire and ultrasound. Results: The primary success rate was 89% (71 of 80 patients) after the first endopyelotomy and increased to 91% (73 of 80 patients) after 2 patients had a second endopyelotomy. After median followup of 26 months (range 1.5 to 72) 6 of the 73 initially successfully treated patients had relapse. Two were successfully re-treated by a second endopyelotomy, resulting in an overall success rate of 81% (65 of 80 patients) after 1 procedure and 86% (69 of 80 patients) after a second endopyelotomy in 4 patients. Mean preoperative pyelocaliceal volume decreased from 64 +/- 33 to 41 +/- 20 ml, (p = 0.0003) 6 months after endopyelotomy and did not change during the following 18 months. The probability of successful endopyelotomy was better in patients with a preoperative pyelocaliceal volume less than 50 ml. (87%) and worse in patients with a volume greater than 50 ml. (76%). A crossing vessel to the lower pole of the kidney causing persistent functional obstruction of the ureteropelvic junction was found in 6 of the 10 patients re-treated by open pyeloplasty (9) or nephrectomy (1). Preoperative mean renal function as determined by diuretic phy was significantly lower in patients with failed endopyelotomy than in successfully treated patients. Successfully treated patients showed no change in renal function 6 and 24 months postoperatively. Conclusions: Endopyelotomy in primary ureteropelvic junction obstruction is a safe, minimally invasive procedure with a high primary success rate and a low relapse rate. Open pyeloplasty could be avoided in 86% of our patients. Endopyelotomy is less invasive, has less functional and esthetic sequelae than open pyeloplasty and does not compromise open surgery if that becomes necessary. We recommend endopyelotomy as Grst line treatment for patients with primary ureteropelvic junction obstruction.