# Evaluation of the Largest Series of Ultramini Percutaneous Nephrolithotomy in Preschool Children: 10-Year Experience with 711 Units of Kidney Stones

## TL;DR

This study shows that a minimally invasive kidney stone removal procedure is safe and effective for young children.

## Contribution

The study presents the largest series of UM-PNL in preschool children with a 10-year follow-up.

## Key findings

- UM-PNL achieved a 96.4% stone-free rate with minimal complications in preschool children.
- The average operation time was 38 minutes, and major complications were rare.
- Most complications were minor and managed without major interventions.

## Abstract

Background and Objectives: This study aimed to evaluate the safety, efficacy and outcomes of ultramini percutaneous nephrolithotomy (UM-PNL) in preschool-aged children with kidney stones. Materials and Methods: A retrospective analysis was conducted on 711 renal units of 676 paediatric patients aged 0–6 years who underwent UM-PNL between April 2014 and July 2024. The children’s demographic data, stone characteristics, operative details and postoperative outcomes were analysed. The procedure was performed using a 9.5 Fr sheath and a 7.5 Fr nephroscope, with laser lithotripsy applied. Postoperative follow-up included imaging and a clinical assessment of complications. Results: The mean patient age was 34.2 months (range: 5–72 months). Haematuria (36.8%) and urinary tract infections (24.5%) were the most common presenting symptoms. The mean stone size was 16.2 mm, and the stone-free rate was 89.2% after the first session, increasing to 96.4% with additional interventions. The mean operative time was 38 min. No major complications were observed; 8.4% of cases had Clavien grade 3b complications, most of which were managed conservatively. Blood transfusion was required in 2.6% of the cases. Conclusions: UM-PNL is a safe and effective treatment method for kidney stones in preschool-aged children, characterized by high stone-free rates and a low risk of complications. With proper patient selection and experienced surgical teams, UM-PNL can be considered a first-line option in paediatric stone management.