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 >2.5 cm, body mass index (BMI) 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, Δ hemoglobin -2.3 g/dl vs. group B, -2.2 g/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, 43 min vs. group B, 68 min, 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.