Endoscopic combined intrarenal surgery: From percutaneous nephrolithotomy to the future of stone management

The surgical management of complex renal calculi has undergone a paradigm shift from traditional prone percutaneous nephrolithotomy (PCNL) to the more versatile supine approach. This evolution paved the way for endoscopic combined intrarenal surgery (ECIRS), a technique that synergizes antegrade and retrograde access into a seamless "four-hand" collaboration. This review explores the historical trajectory and biomechanical advantages of ECIRS, emphasizing its role in overcoming the limitations of PCNL and retrograde intrarenal surgery monotherapies. Central to this approach is the "intermediate-supine position," which facilitates real-time simultaneous operation. We highlight critical mechanisms such as the "transport technique," where flexible ureteroscopy displaces inaccessible fragments toward the nephroscope, and the "washout mechanism," which maintains low intrarenal pressure and ensures clear visualization. Contemporary evidence, including recent randomized trials and meta-analyses, demonstrates that ECIRS-particularly with miniaturized tracts (Mini-ECIRS)-achieves superior stone-free rates with significantly reduced morbidity compared to conventional methods. The technique proves especially advantageous for staghorn calculi and high-risk patients by enabling "single-puncture" clearance, thereby minimizing hemorrhagic risks associated with multiple tracts. Furthermore, the integration of robotic assistance for both renal access and retrograde manipulation is democratizing technical excellence. As we transition toward the era of "Fully Robotic ECIRS," this multimodal strategy is increasingly positioned not merely as an alternative, but as a leading framework and a strong candidate for broader adoption in appropriately selected patients with for complex urolithiasis, balancing maximal clearance with minimal invasiveness.