Robot-assisted advancing spiral flap pyeloplasty for complex ureteropelvic junction obstruction and ureteral atresia: a preliminary experience in 27 patients.

BACKGROUND

Long-segment ureteropelvic junction obstruction (UPJO) (typically 12≥3 cm) and ureteral atresia present major reconstructive challenges due to fixed-length limitations of conventional flap techniques. This study evaluates the feasibility and safety of a robot-assisted advancing spiral flap pyeloplasty (RASFP) with dynamically adjustable flap design as a proof-of-concept for complex cases.

METHODS

A single-center retrospective study (August 2022-July 2025) included 27 patients with long-segment UPJO (median stricture length 3 cm) or ureteral atresia. All patients underwent RASFP using two intraoperatively tailored flap configurations (anterograde/retrograde) without pre-determined length constraints. Primary outcomes were feasibility and safety; secondary outcomes included functional, radiological, and clinical improvement.

RESULTS

All 27 procedures were completed robotically without conversion or major complications (Clavien-Dindo ≥II). The technique successfully managed all six ureteral atresia cases without grafts and bridged a 7-cm stricture. At median follow-up of 14 months, symptomatic relief was achieved in 88.9% of patients, and median hydronephrosis diameter decreased from 3.8 cm to 2.0 cm (P=0.01). Median eGFR increased by 1.6 mL/min. In complex cases (stricture ≥4 cm, atresia, or redo pyeloplasty, N.=16), clinical symptom relief was achieved in 87.5% (14/16) and radiological improvement in 81.3% (13/16). Postoperative CT urography in four patients confirmed obstruction relief in three.

CONCLUSIONS

In this preliminary series, RASFP demonstrated acceptable safety and feasibility for carefully selected patients with complex UPJO and ureteral atresia who have a dilated renal pelvis. The technique may offer a potential tissue-sparing option for ultra-long strictures and atresia where conventional flaps may be inadequate. Comparative studies are needed to establish its relative efficacy.