Endourologic Management of UPJO 　With the patient in the dorsal lithotomy position, a 0.038-inch guidewire was inserted into the lower pole of the collecting system, and an AcuciseⓇ cutting wire was pre- aligned in the posterolateral position. We introduced the AcuciseⓇ over the guide wire and advanced it just proximal to the UPJ stricture. Under C-arm fluoroscopy, the AcuciseⓇ Cautery balloon wire was used to incise the narrowed ure- teropelvic junction in the posterolateral direction. The op- erative retrograde pyelography confirmed a successful in- cision of the narrowed ureter through extravasation of con- trast medium. A 6 Fr stent was placed in the lower collect- ing system for 6 weeks. An intravenous pyelography at 3 months postoperatively showed marked reduction of the FIG. 2. The 3-month postoperative IVP showing definite decomp- ression of the lower pole obstruction. IVP: intravenous pyelo- graphy. 435 hydronephrosis in the lower pole moiety (Fig. 2). Case report 2 A 54-year-old man was referred to our institution for inves- tigation of persistent pyuria. The abdominal computerized tomography demonstrated an incompletely duplicated col- lecting system on the right side with marked hydro- nephrosis and multiple renal stones of the lower pole moi- ety (Fig. 3). Retrograde pyelography confirmed the find- ings and revealed that the lower pole pelvis was extremely dilated with grade III hydronephrosis, which suggested concomitant lower pole UPJO (Fig. 4A). On the basis of these findings, a right lower pole UPJO associated with multiple renal stones with an incomplete duplicated col- lecting system was diagnosed, and an antegrade endouro- logic procedure was planned. 　Cystoscopy and then retrograde pyelography were per- formed and showed narrowing at the UPJ at the right lower moiety, with severe dilation of the adjacent lower pole of the renal pelvis. A ureteral catheter was inserted at the lev- el beneath the UPJ of the lower pole moiety. 　Next, the patient was placed in a prone position, and ret- rograde instillation of contrast was performed to opacify the pelvicocaliceal system. Percutaneous access was estab- lished at the mid calyx, and then tract dilation was per- formed by balloon dilation with a 30 Fr catheter at a pres- sure of 12 atm. Through the 30 Fr Amplatz sheath, the stones were fragmented by using a pneumatic lithotriptor under fluoroscopic control. All stone extractions were suc- cessful, and we found no evidence of residual calculi on imaging. 　After a 21 Fr sheath was advanced up to the renal pelvis, the UPJO was identified easily. The narrowed ureter was incised with a cold knife as far as the periureteral fat and visualized widely. A 6 Fr Double J stent was placed in the FIG. 3. Preoperative computed tomography showing marked hydronephrosis and multiple renal stones of the lower moiety (A) Computed tomography showing incomplete duplication with dilatation of the right lower pole moiety. (B) Multiple renal stones in the lower pole moiety. Korean J Urol 2010;51:434-437