Microperc for Pediatric Nephrolithiasis: Technique in Valdivia-Modified Position

<b>Introduction</b> Micropercutaneous nephrolithotomy (microperc) has been recently proposed in adult patients. We present our initial experience in children using a modified technical approach. <b>Methods</b> After the retrograde positioning of a 5F catheter, a 4.85F metallic needle (1.9 mm) was used for direct percutaneous calyceal access under ultrasonographic and fluoroscopic guidance with the patient in supine Valdivia-modified position. Once a three-way connector was inserted to the needle, stone fragmentation was performed under direct vision using a 200 μm holmium:YAG laser fiber and a 0.9-mm high-resolution (10,000 pixels) optic flexible wire connected with the telescope, with intermittent saline infusion. The transureteral catheter was removed within 18 to 24 hours. <b>Results</b> A total of five patients aged 18 months to 11 years (mean, 5.8 years) received microperc lithotripsy in a 6-month period. The mean stone size was 15.0 mm (±2.5 mm). Conversion to retrograde intrarenal surgery was necessary in one case, due to stone migration and poor visibility. Moderate hydronephrosis was present in one kidney. The mean operative time was 56 minutes (±23 minutes). The blood loss was insignificant (< 0.6 Hbg/dL) and postoperative discomfort was minimal. The mean hospital stay was 2.4 ± 0.6 days for four patients after the removal of ureteral catheter. The JJ stent was removed after 15 days in the last patient. The overall stone-free rate at 1 month was 100% and no ancillary procedures were required. <b>Conclusions</b> Microperc is a new cost-effective and time-saving technique that we demonstrated as safe and effective in minimally invasive procedure for lower pole and pelvic renal stones of small size. Indications and limits should be defined by multicenter randomized studies, comparing the former procedures.