Implementation of Ultramini Percutaneous Nephrolithotomy for Treatment of 2–3 cm Kidney Stones: A Preliminary Report

Background and Purpose: Miniatured percutaneous nephrolithotomy (PCNL) techniques such as micro-PCNL (microperc) and ultramini-PCNL (UMP) are usually indicated for renal stones <2 cm. We present our preliminary report of treating patients with 2 to 3 cm renal stones using UMP in a semisupine combined lithotomy position associated with a retrograde ureteral access sheath (UAS).

Methods: From April 2013 to January 2014, we implemented 13F UMP for 22 patients with renal stones that were 2 to 3 cm with the patient positioned in a 45-degree semisupine combined lithotomy position. A retrograde 9.5/11.5F UAS was placed for maintaining low intrarenal pressure and debris drainage. Flexible ureteroscopy was used for stones inaccessible through the primary percutaneous tract in two patients. A 200-μ holmium laser was used for stone disintegration. Intrapelvic pressure was measured using an open end 5F ureteral catheter inserted through the UAS.

Results: All 22 cases were completed successfully. The mean preoperative stone size was 26.6 ± 4.7 mm (range 21–32 mm), mean operative time was 85.7 ± 18.0 minutes (range 47–112 min), and mean hemoglobin drop was 1.2 ± 0.3 g/dL (range 0.5–2.2 g/dL). Intrapelvic pressure during the surgical procedure ranged 5 to 10 cm H₂O. The mean hospital stay was 3.1 ± 1.8 days (range 2–5 d). Complete stone clearance was 18/22 (81.8%) with solo UMP and 20/22 (90.9%) when associated with retrograde intrarenal surgery (RIRS). No major intra- or postoperative complications occurred.

Conclusion: Implementation of UMP for the treatment of patients with renal stones 2–3 cm is feasible and safe. The procedure is less invasive and has a faster recovery period. Intraoperative retrograde UAS decreases intrarenal pressure, facilitates removal of stone fragments, and also allows simultaneous RIRS for stones in an inaccessible calix.