60 patients after PCNL will be recruited and randomized into 2 groups (30 vs 30):~No Catheterization after mini-PCNL (study) - the bladder catheterization is not performed.~Catheterization after mini-PCNL (control) - the bladder will be drained with the urethral catheter.~All patients will fill out the VASP in 2, 6, 12, 24 hours after mini-PCNL. Ultrasound examination of urinary bladder will be performed after mini-PCNL. All the AE will be registered.
60 patients~Inclusion Criteria:~age from 18 to 70 years~Indications for mini-PCNL~ASA score: 1-3~Single percutaneous access to pyelocaliceal system~Size of solitary calculus up to 2.5 cm~Exclusion Criteria:~Active urinary tract infection~Coagulopathy~Clinically significant infravesical obstruction (Qmax less than 10 ml / s, PVR more than 50 ml)