The aim was to evaluate the surgical learning curve and advantages of top-dow two-knot laparoscopic pyeloplasty in children with uretero-pelvic junction obstruction (UPJO).
Materials and methods. A retrospective analysis of medical records regarding 98 patients from Speranskij Children’s Municipal Hospital №9, Moscow and Regional Clinical Hospital №7, Volgograd, aged from 3 to 24 months with unilateral hydronephrosis of varying degrees, according to the SFU classification (Society of Fetal Urology) in the Onen modification was carried out.
LP in all children was performed in accordance with the Heins-Andersen technique, with minimal resection of the pelvis. In order to compare different techniques for the formation of pyeloureteral anastomosis, patients are divided into two groups: on the first group (n=59) TDTKT was performed, and on the second (n=39) – the standart knotting technique (SKT) was performed. The patients were operated by two surgeons from different clinics. Average time of operation, learning curves, frequency of post-operative complications and post-operative assessments were included as criteria for the comparison of the two groups.
Results. Using TDTKT allowed a reduction in mean time of surgery of 30%. Positive results were obtained in both groups of patients by reducing the degree of hydronephrotic transformation of the kidney during their follow-up year.
Conclusion. Using TDTKT not only permits an experienced surgeon to reduce his duration of operation to 67.86 minutes, it also positively affects the surgical learning curve for less experienced surgeons. In this regard, this technique can be recommended to surgeons who do not have much experience in conducting laparoscopic pyeloplasty.

Keywords: descending two-knot technique, laparoscopic pyeloplasty, pediatric urology, hydronephrosis