Percutaneous nephrolithotomy in obese patients: comparison between the prone and total supine position.

Background: Percutaneous nephrolithotomy (PCNL) can be performed in the prone or in the supine position. Comparisons between the two techniques in obese patients are rare in the current literature.

Methods: The records of obese patients (body mass index >30) who underwent PCNL in the prone or complete supine positions were reviewed. All patients had a noncontrast CT before and after the procedure. Stones were graded according to the Guy stone score and complications according to the Clavien grading. The stone-free rates, operative time, surgical complications, and hospital stay were analyzed.

Results: A total of 56 PCNL were performed in 42 patients. Twenty-four PCNL were performed in the prone and 32 in the total supine position. Stone-free rate on the first postoperative day was 50% in the prone and 46.9% in the supine position (P=1.0). Final stone-free rates were 83.3% and 78.1%, respectively (P=0.74). Mean operative time was 164.6 minutes in the prone and 120.3 minutes in the supine position (P=0.0017), and hospital stay was 4.38 and 2.68 days (P=0.014), respectively. The transfusion rate was 20.8% in the prone and zero in the supine position patients (P=0.01). Excluding Guy IV stones, transfusion rate was 8.3% in the prone position (P=0.1). Significant surgical complications rate was 12.5% in the prone and 3.1% in the supine position (P=0.302).

Conclusion: PCNL performed in the prone or in the complete supine position in obese patients presents similar outcomes. The supine decubitus position has the advantages of a significantly shorter operative time and hospital stay.