The learning curve for a single surgeon using ultrasonography to guide supine percutaneous nephrolithotomy with an alken metal telescopic dilator

Ultrasound (US) has three advantages over fluoroscopy for guiding percutaneous nephrolithotomy (PNCL): it provides an assessment of adjacent structures and real-time puncture adjustment, and is radiation free. This study aimed to define the number of procedures that should be performed to achieve competence in US-guided PCNL using an Alken metal telescopic dilator. A non-randomised retrospective study with consecutive sampling was used for the study design. A total of 50 patients above 18 years of age with the largest diameter of renal stone ≥20 mm were included. They were divided into five groups based on timing of the surgery to evaluate and visualise improvements based on primary outcomes within the groups. Line charts were used, and statistical analysis was performed to evaluate the learning curve. Most of the base characteristics between the groups were similar. Tract dilatation time decreased significantly after 20 PCNLs were performed (p < 0.001). Stone-free status markedly increased after 20 PCNLs were performed (p < 0.001). Postoperative fever (10%) and need for blood transfusion (26%) were the only complications. Basic competency was achievable after 20 PCNL procedures were performed, and further improvements in outcomes were achieved after 40 PCNLs with an acceptable rate of non-severe complications.