Endourologic Management of UPJO commodate an endopyelotomy stent, and a long, (＞2 cm) stenosed ureteropelvic segment. But, even in these cases of endourologic failure, salvage pyeloplasty can provide long-term patency, especially if the failure is due to an ini- tially missed crossing vessel or a redundant renal pelvis. Braga et al reported a 100% success rate after salvage pye- loplasty over an average follow-up of 47 months [10]. 　Although open pyeloplasty remains the standard treat- ment, the minimally invasive endoscopic procedures are an attractive option and could be the first line of treatment if proper patient selection is used, for example, for UPJO re- sulting from an aperistaltic segment or minor stricture in the absence of a crossing vessel. With respect to long-term outcomes, these endourologic procedures may be limited, but endourologic failures can be salvaged with pyeloplasty in most cases. Conflicts of Interest The authors have nothing to disclose. REFERENCES 1. Cooper CS, Snyder HM 3rd. Embryology and physiology of the ureter. In: Sydor AM, editor. Adult and pediatric urology. 4th ed. Philadelphia: Lippincott Williams & Wilkins; 2002;2156-8. 437 2. Shelfo SW, Keller MS, Weiss RM. Ipsilateral pyeloureterostomy for managing lower pole reflux with associated ureteropelvic junc- tion obstruction in duplex systems. J Urol 1997;157:1420-2. 3. Ruano-Gil D, Coca-Payeras A, Tejedo-Mateu A. Obstruction and normal recanalization of the ureter in the human embryo. Its rela- tion to congenital ureteric obstruction. Eur Urol 1975;1:287-93. 4. Johnston JH. The pathogenesis of hydronephrosis in children. Br J Urol 1969;41:724-34. 5. Jerkins GR, Noe HN. Unusual presentation of ureteropelvic junc- tion obstruction in an incomplete duplex system. Urology 1985; 26:402-4. 6. Doo CK, Hong B, Park T, Park HK. Long-term outcome of endo- pyelotomy for the treatment of ureteropelvic junction obstruction: how long should patients be followed up? J Endourol 2007;21:158-61. 7. Goldfischer ER, Jabbour ME, Stravodimos KG, Klima WJ, Smith AD. Techniques of endopyelotomy. Br J Urol 1998;82:1-7. 8. Nakada SY, Johnson M. Ureteropelvic junction obstruction. Retrograde endopyelotomy. Urol Clin North Am 2000;27:677-84. 9. Koh JS, Lee DH, Kim DB, Cho SY. Endopyelotomy and endour- eterotomy with the ureteral cutting balloon device (AcuciseⓇ). Korean J Urol 2006;47:818-23. 10. Braga LH, Lorenzo AJ, Skeldon S, Dave S, Bagli DJ, Khoury AE, et al. Failed pyeloplasty in children: comparative analysis of retro- grade endopyelotomy versus redo pyeloplasty. J Urol 2007; 178:2571-5. Korean J Urol 2010;51:434-437