Objective: To assess the stone-free rate (SFR) and safety of our new modified technique of mini-percutaneous nephrolithotomy (mini-PCNL) using counter-irrigation through a separate upper pole access.

Methods: The medical data of 40 patients with kidney stones (<30 mm) and a dilated upper calyx treated with our novel modification of mini-PCNL between August 2020 and October 2021 were prospectively collected and analysed. Stone-free status of the patients was evaluated at 3 days and 1 month post-operatively via abdominal and pelvic non-contrast computed tomography (NCCT).

Results: The mean stone size was 24.68 ± 2.86 mm, and the mean stone density was 931.38 ± 308.92 hounsfield unit (HU). The mean total operative time was 78.8 ± 13.62 min, while the mean time required for placing the upper calyceal nephrostomy tube was 3.76 ± 1.25 min. Immediate overall SFR was 90%, which reached 95% at the 1-month follow-up. The overall complication rate was 10% (four patients), including fever (38 °C) that required antipyretics in two (5%), fever (38 °C) that necessitated hydration and IV antibiotics in one (2.5%), and persistent mild haematuria that improved with coagulants and excess fluid intake in one (2.5%).

Conclusions: Counter-irrigation in mini-PCNL for a renal pelvic stone with a dilated upper calyx is an encouragingly safe and effective option. This novel technique provides a potentially high SFR and acceptable safety profile via enhanced intra-operative visualisation, decreased stone migration, and better washout of stone fragments.