Modified supine versus prone position in percutaneous nephrolithotomy for renal stones treatable with a single percutaneous access: a prospective randomized trial

OBJECTIVES: To compare operative time, safety, and effectiveness of percutaneous nephrolithotomy in the supine versus prone position in a prospective randomized trial. MATERIAL AND METHODS: From October 2005 to June 2007, 75 patients (33 men, 42 women; mean age, 39.3 yr) were prospectively enrolled and randomly divided into group A (39 patients, supine position) and group B (36 patients, prone position). Inclusion criteria were diagnosis of single or multiple renal stones (pelvic-caliceal) treatable with a single percutaneous access, stone diameter >2.5cm, body mass index (BMI) <30kg/m(2), and no contraindications to perform the operation in the prone position. Exclusion criteria were stones in more than one calyx, complete staghorn stones, and coexisting renal anomalies. RESULTS: The two groups were comparable in age, BMI, male-to-female ratio, and stone size. No significant difference was ascertained between the two groups in terms of stone-free rate (group A, 88.7% vs. group B, 91.6%, p=0.12), mean blood loss (group A, Delta hemoglobin -2.3g/dl vs. group B, -2.2g/dl, p=0.23), and mean hospital stay (group A, 4.3 d vs. group B, 4.1 d, p=0.18). The only significant difference reported was mean operative time (group A, 43min vs. group B, 68min, p<0.001). No blood transfusions were needed and no organ injuries were reported. CONCLUSIONS: In this carefully selected patient population with uncomplicated renal stones, the supine position was similar to the prone position for percutaneous stone removal.