Introduction. Currently, percutaneous nephrolithotripsy is the main treatment for large and coral-like kidney stones in children.

The purpose of the study was to increase the effectiveness of percutaneous nephrolithotripsy (PCNL) in children using miniature-sized instruments.

Materials and methods. For the period from 2008 to 2019, 320 children aged 1 to 17 years underwent nephrolithotripsy in the pediatric department of the N. Lopatkin Scientific Research Institute of Urology. Depending on the size of the instruments used, patients were divided into 3 groups. The first group included children who underwent surgery using the Mini-PCNL technique (n-211), the second group included patients operated on using the Ultra-Mini-PCNL method (n-16) and the third group included children whose percutaneous intervention was performed using a standard-sized nephroscope (n-93). The intervention was carried out according to the standard method; all patients underwent cystoscopy, catheterization of the ureter, access formation, lithotripsy, lithoextraction and installation of nephrostomy drainage.

Results. In the first group of children studied, complete elimination of clinically significant stones (residual stones smaller than 4 mm) after the initial intervention was achieved in 169 (80.1%) pediatric patients. In the second group, there was 13 (81.2%) children. And in the third group, getting rid of stones was achieved in 73 (78.5%) patients. The average time required to perform surgery in all three study groups was comparable and amounted to 45 (40-125) minutes in the first group, 40 (25-85) minutes in the second, and 50 (40-180) minutes in the third group. The final efficacy of percutaneous nephrolithotripsy in children using instruments of various sizes in the first group was 89.6%, in the second – 93.7% and 88.1% in the third study group. The hospital stay after surgical treatment was: 4 (3-12) days for the first group, 3.5 (3-7) and 4.5 (3-17) days for the second and third groups, respectively. The need for additional interventions after PCNL in pediatric patients was in 69 (32.7%) children in the first group, 4 (25%) in the second and 41 (44.1%) in the third group.

Conclusion. The use of mini-PCNL, ultra-mini-PCNL can reduce the duration of surgical intervention by 10% and 20%, the hospital stay after PCNL by 11.2% and 22.3%, the need for additional interventions by 11.4% and 19.1%. Can reduce the total number of complications by 10% and 12.2%, respectively, compared with the use of standard-size instruments. The use of Mini-PCNL in children is indicated in the younger and middle age groups, Ultra-Mini-PCNL is indicated for single stones up to 2 cm or as an additional access in the multi-accesses formation.