Flank-Free Modified Supine Prone Ultra-Mini-Percutaneous Nephrolithotomy in Treatment of Medium-Sized Renal Pelvic Stone: A Randomized Clinical Trial.

Percutaneous nephrolithotomy (PCNL) is the standard treatment of renal stone >2 cm. Ultra-mini-percutaneous nephrolithotomy (UMP) had emerged in the past decade as a new technique in treating renal stones <2 cm. In this study we compared between the outcome of UMP in prone position with the outcome of UMP in modified flank free supine position (FFSP). A prospective randomized study was conducted between January 2016 and April 2020, including 122 patients, divided into two matched groups. Group A included 61 patients who underwent UMP in FFSP, and Group B included 61 patients who underwent UMP in a prone position. All patients had a single renal pelvic stone 1-2 cm. Patients with a single kidney, renal anomalies, body mass index ≥40 kg/m, history of ipsilateral renal surgery, and age <18 years were excluded. In both groups, the dilatation was done up to 13F; a holmium laser was used through a 9F ureteroscope for fragmentation. Nephrostomy tube and ureteral stent were used only when indicated. In total, 122 patients were divided into two groups. The mean age was 40.09 ± 13.63 and 39.67 ± 13.80 years in both groups, respectively. The operative time was 63.64 ± 9.22 and 78.48 ± 9.55 minutes in Groups A and B, respectively ( = 0.0001). The fluoroscopy time was 3.47 ± 0.56 and 4.45 ± 0.39 minutes in Groups A and B, respectively ( = 0.0001). No significant difference was shown between both groups regarding operative and postoperative complications. Shift to mini-PCNL was needed in one patient in Group A and four patients in Group B because of impaired vision. The hospital stay was 25.36 ± 4.23 and 26.13 ± 4.76 hours in both groups, respectively. The initial stone-free rate was 95.1% and 91.8% in both groups, respectively. UMP in modified supine position shows comparable results with UMP in the prone position regarding stone-free rate, hospital stay, and perioperative complication, with significantly shorter operative and fluoroscopy time.