Prospective Evaluation of Learning Curve of Urology Residents for Percutaneous Nephrolithotomy

Abstract

IntroductionWe studied the learning curve for percutaneous nephrolithotomy of urology residents according to stone complexity. MethodsThe learning curve of 8 residents with no previous experience of solo percutaneous nephrolithotomy was studied. Stones were classified according to complexity using the Guy stone score. Competence was reviewed using 4 markers, namely operative time, fluoroscopic time, complication rate using the modified Clavien grading system and success rate. Analysis was done in 3-month cohorts to determine how and when competence and excellence were achieved during 1 year of training for various grades of stone. The results of resident surgeons were compared with those of experienced endourologist. ResultsResident surgeons achieved a plateau in mean operative time and fluoroscopic time for grade I stones after 30 to 35 cases but not for more complex stones. Similarly complications were decreased significantly only in grade I stone cases. Resident surgeons also achieved an almost excellent success rate of 87% for grade I stones only. ConclusionsThis study of the learning curve of residents suggests that competence and near excellence is reached after 30 to 35 cases for grade I stones. However the learning curve for complex stones (grades II to IV) is steeper and requires more experience.