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 ureterop elvic junction obstruction. Materials and Methods: In 80 consecutive p atients primary ureteropelvic junction obstruction was diagnosed by ex cretory urogram or nephrostomogram, retrograde pyelography, diuresis r enography and the Whitaker test in ambiguous cases. In all patients an tegrade endopyelotomy was performed with a cold knife and an indwellin g stent was left for 6 weeks. At 6 and 24 months postoperatively resul ts were assessed clinically by an excretory urogram and/or diuretic re nography and later by questionnaire and ultrasound. Results: The prima ry success rate was 89% (71 of 80 patients) after the first endopyelot omy and increased to 91% (73 of 80 patients) after 2 patients had a se cond endopyelotomy. After median followup of 26 months (range 1.5 to 7 2) 6 of the 73 initially successfully treated patients had relapse. Tw o 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 4 1 +/- 20 ml, (p = 0.0003) 6 months after endopyelotomy and did not cha nge during the following 18 months. The probability of successful endo pyelotomy was better in patients with a preoperative pyelocaliceal vol ume 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 junctio n 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 endopyel otomy than in successfully treated patients. Successfully treated pati ents showed no change in renal function 6 and 24 months postoperativel y. Conclusions: Endopyelotomy in primary ureteropelvic junction obstru ction is a safe, minimally invasive procedure with a high primary succ ess rate and a low relapse rate. Open pyeloplasty could be avoided in 86% of our patients. Endopyelotomy is less invasive, has less function al 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.