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[Evolution from Percutaneous nephrolithotomy to Mini-PCNL in supine position on the treatment of complex renal calculi: feasibility study.]

OBJECTIVES
Mini-PCNL is a potentially less invasive technique than standard percutaneous nephrolithotomy (PCNL). We present our experience and results comparing both approaches in large burden complex renal calculi.


METHODS
Prospective non randomized study comparing PCNL (24/26F nephroscope; Group A) and Mini-PCNL (15/18F; Group B) perioperative and postoperative results, in 40 (20 each group) consecutive patients between 2013 and 2014. We analyze demographic data, hemoglobin drop, urine culture, stone characteristics, operative time, puncture, number and size of the tract, disintegration energy sources, nephrostomy placement, hospital stay, stone free rate and Clavien-Dindo complications.


RESULTS
Evolution has shown growth for Mini-PNL, with the last 17 consecutive cases performed by this approach. No preoperative differences in laterality, age, gender or ASA were found; but there were differences in BMI (median Group A: 26.35 kg/m2; Median Group B: 33.05 kg/m2, p = 0.008). Median calculi surface area (SA = length × width × π × 0.25) was higher for mini-PNL (6.69 cm2 vs 14.14; p=0.003). The operative time was longer for mini-PNL (120 vs 162.5 min, p = 0.03). Only one case (5%) required transfusion in NLP 24/26F. Mini-PCNL was associated with tubeless technique (55%) (p = 0.022), which explains lower 24 h postoperative pain, after surgery, measured by VAS (p =0.0004). The hospital stay was equivalent (median: 2 days; p=0.8). Both techniques showed efficacy (SFR at 3 months 80%). There were no statistically significant differences between the number and severity of complications between groups (Group A: 15%, 66.7% Clavien II, Group B: 15%; 66.7% Clavien II, p = 1).


CONCLUSIONS
Mini-NLP can manage kidney stones and even large staghorn calculi without nephrostomy in a high percentage of patients. The technical evolution towards a small caliber approach maintains the effectiveness of the procedure without impacting its safety, with benefits perceived by patients such as less postoperative pain.