Purpose of review: Miniaturization was the major trend in percutaneous nephrolithotomy in the past 15 years, aiming to lower tract-size-related complication rates while maintaining good stone-free-rates (SFR). Although there is some evidence that 18 Fr Mini-percutaneous lithotomy (PCNL) has comparable efficacy to conventional PCNL and a lower risk of bleeding, it is less clear whether further miniaturization led to an even better safety profile while maintaining good SFR. The present review evaluates the latest results on efficacy, safety, and feasibility of miniaturized techniques 14 Fr or less in PCNL.
Recent findings: Recent literature of the last 2 years reported outcomes of different systems from 4.85 to 14 Fr. Most of these studies demonstrated good efficacy when comparing with RIRS or conventional PCNL. Limitations were a decrease in SFR for stone sizes more than 2 cm, a longer operative time and the likelihood of pathologic intrarenal pressure (IRP) with a higher risk of postoperative fever or sepsis.
Summary: Miniaturization of PCNL is an innovative approach in order to lower complication rates and hospitalization time for therapy of renal stones. Limitations like longer OR time or higher IRP may limit the benefit of super miniaturized systems. Currently, the 18 Fr Mini-PCNL seems to be the most reliable solution for stones up to 25 mm, whereas RIRS remains the first choice in renal stones less than 10 mm.