Adopting for Supine Percutaneous Nephrolithotomy: Analyzing the Learning Curve of Tertiary Academic Center Urology Team

Objectives: To evaluate the effect of learning curve on supine mini-percutaneous nephrolithotomy (PNL) outcomes.

Methods: The aim of the study was to include a total of 75 patients. All of the patients were operated on by the same team, which had experience of at least 100 prone mini-PNL cases. The team was led by a surgeon who had observed 40 supine conventional PNL procedures (sheath size 24 Fr) over a period of 3 months at an endourology center with experience in supine PNL and surgeries were performed by the same primary surgeon. Patients were divided equally into 5 groups, as first 15 cases in Group 1, and final 15 in Group 5. Groups were compared according to preoperative characteristic, intraoperative result, complication rate, and success rate.

Results: The mean access time was 14 minutes in group 1. It decreased to mean of 10.3 minutes for cases 31 through 45, and afterward significant decrease occurred up to a mean of 6.5 minutes for cases 61 through 75 (P ≤.001). According to the Clavien-Dindo classification system, complications were assessed, and a decrease was observed from group 1 to group 5 (40%, 20%, 26.6%, 6.7%, and 13.3%, respectively). The stone free rate increased from the mean of 66.7% for the first two groups to 80% for group 3 and increase up to the 93.3% for group 4 and 5 (P = .128).

Conclusion: The present study showed that considering the decrease in access time and operation time 60 patients could be enough for surgical competency as well as the complications and stone-free rates reached satisfactory levels after 45 patients.