Initial Drainage Method and Flexible Ureteroscopy Outcomes in Calculous Anuria

Calculous anuria caused by obstructing upper ureteral stones in a solitary functioning kidney is a urological emergency requiring urgent decompression. Both retrograde JJ ureteral stenting and percutaneous nephrostomy are commonly used emergency drainage methods. However, limited evidence is available regarding whether the initial drainage method affects subsequent definitive flexible ureteroscopy/retrograde intrarenal surgery outcomes. This multicenter prospective randomized controlled trial will compare emergency JJ ureteral stent drainage versus percutaneous nephrostomy drainage in adult patients presenting with calculous anuria due to a single upper ureteral stone in a solitary functioning kidney. After renal functional improvement, clinical stabilization, and appropriate urine culture management, all participants will undergo standardized definitive flexible ureteroscopy/retrograde intrarenal surgery. The study will assess renal functional recovery, first-session surgical success, stone-free rate, operative parameters, complications, and microbiological outcomes.

Inclusion Criteria: * Adults aged 18 years or older. * Calculous anuria secondary to a single upper ureteral stone. * Solitary functioning kidney, whether anatomical or functional. * Single upper ureteral stone confirmed by non-contrast computed tomography. * Stone size from 6 mm to 20 mm in maximum diameter. * Patient considered suitable for either initial JJ ureteral stent drainage or percutaneous nephrostomy drainage. * Candidate for definitive treatment by flexible ureteroscopy/retrograde intrarenal surgery. * Documented renal functional improvement and clinical stabilization before definitive RIRS. * Negative or appropriately treated urine culture before definitive RIRS. * Ability and willingness to provide written informed consent. Exclusion Criteria: * Multiple stones or bilateral stones not fitting the solitary-kidney study design. * Renal pelvic, distal ureteral, or multiple ipsilateral stones. * Stone burden greater than 20 mm. * Septic shock, hemodynamic instability, or need for emergency dialysis at presentation. * Pyonephrosis requiring a non-randomized drainage decision. * Anatomical abnormalities affecting endoscopic access, such as horseshoe kidney, pelvic kidney, ureterocele, or ureteral stricture. * Previous ipsilateral ureteral reconstructive surgery. * Uncorrected coagulopathy. * Pregnancy. * Genitourinary malignancy. * Inability to complete follow-up.