To evaluate the effects of location of the tip of percutaneous sheath and nephroscope in the collecting system together with active aspiration on the Intrapelvic pressure measurements (IPP) during miniaturized percutaneous nephrolithotomy (miniPNL).

The data of 20 patients underwent miniPNL in supine position was collected prospectively. IPP measurements were done with an 8 Fr urodynamic pressure measurement catheter in 4 different settings with respect to location of tip of sheath and nephroscope. All 4 settings were repeated with active aspiration. Totally measurements were done and compared in 8 different settings for 90 seconds in each patient.

Highest mean IPP measurements were recorded in setting II (35.3 ± 11.8 cm H2O) where the sheath was located in the calyx and the tip of the nephroscope was in the renal pelvis. When active aspiration was applied, the mean pressure measurements were significantly lower than the counterpart settings without aspiration (all P values <.0001). When the active aspiration was applied, intrarenal pressure measurements did not exceed 40 cm H2O in any settings in any of the patients.

Location of the tip of the sheath and the nephroscope has significant effect on IPP measurements. Active aspiration significantly lowers the IPP and keeps it <40 cm H2O. Endourologists should be aware of possible alterations in IPP during miniPNL and active aspiration should be kept in mind as an effective solution to decrease the risk of complications related to high IPP.