Complete stone clearance using a modified supine position: initial experience and comparison with prone percutaneous...

The recently described Galdakao-modified supine Valdivia position for percutaneous nephrolithotomy (PCNL) has become increasingly popular. We have made further modifications to this and describe our recent experience compared with our previous prone cases.

From April 2011, all patients undergoing PCNL have been placed in the modified supine position. A suction beanbag is used to secure the patient and improve renal access. Data on patient age, comorbidities, stone size, operative time, radiation exposure, complications, stone clearance, and length of stay was collected, analyzed, and compared with data from our previous year's prone surgery.

Thirty-six patients in each group underwent 41 PCNLs. The groups were well matched for age, sex, and comorbidity. The supine patients tended to have a higher body mass index. Stones in the supine group were larger (32.6 vs 25.7 mm, P=0.0402), and the operative time was shorter (86.2 vs 116.6 min, P=0.003). Radiation time was similar in the two groups, but the dose was higher in the supine group. Stone clearance rates, length of stay (2.5 days), and complications were similar. Nineteen (46%) patients underwent simultaneous lower urinary tract procedures including 4 (10%) with complete staghorn calculi for which ureterorenoscopy was used to fragment ureteral and upper renal pole stones.

The modified supine position for PCNL has a number of advantages for the patient and staff compared with the prone position. Despite a more obese study group with larger stones, we have maintained stone clearance rates and significantly reduced operative time with no increase in complications. The technique has been easy to learn and teach. A major advantage has been simultaneous access to the lower urinary tract for ureteroscopy and stent placement, and this has helped with complete stone clearance.