Introduction. The efficacy of antegrade laser endopyelotomy (ALM) for ureteropelvic junction (UPJ) obstruction (UPJO) in pediatric patients is yet not defined. 

Materials and methods. Percutaneous ALM was performed in 36 pediatric patients with mean age of 6.3 years (range 2-17 years) in a period of 20082014 years. All patients were earlier operated on using open (32) or laparoscopic (4) UPJO correction. Dilatation of the renal system, decrease in renal function and chronic pyelonephritis were the common indications for ALM. Renal stones 0.6 up to 12 mm were concurrent in 14 patients (38.9%). Mean stricture length was 0.75 cm (range 0.2-1.0 cm). Nephroscopes with different diameters were used (9.5Ch, 15Ch, 22Ch and 22Ch). Upper pole calix was accessed. Holmium laser was used for longitudinal stricture transection across all layers. Laser or contact lithotripsy (LithoClast Master) was used to disintegrate the stones. Stent 5-7 Ch and nephrostomy tube were leaved at the end of the procedure. Residuals stones were cleared using ESWL. 

Results. Mean operation time was 51.6 min (42-84 min). No complications were evident. Mean stay in hospital was 3.4 days. Late outcomes (followup range from 6 months up to 5 years) showed good results in 30 patients (83.3%), which all had the strictures shorter than 8 mm. Six patients (16.7%) with extended strictures failed to achieve the stability and were operated on later using laparoscopic UPJO correction with good overall results. 

Conclusions. Percutaneous ALM is effective in patients with short recurrent strictures of UPJ (5-8 mm) with preserved renal function and highly effective in case of ligature nephrolithiasis. Contraindication would be a primary inborn hydronephrosis and crossing vessels. Patients with extended strictures (>10 mm) and obliterations with substantial decrease in renal functions demonstrate poor outcomes after ALM.