Destruction of renal parenchyma at percutaneous nephrolithotripsy; experimental study

The destruction of renal parenchyma caused by excess deflection of the sheath was examined to determine at what level of force the renal parenchyma was ruptured during PNL. The kidney obtained from right nephroureterectomy due to renal pelvic cancer (stage T2N0M0) of a 54-year-old female patient was punctured at the posterolateral portion with a puncture needle. The tract was dilated up to 26 Fr. in size with an Amplatz renal dilation set. The 26 Fr. sheath was left in the tract and fixed to the metal bar attached to Gig Boring Machine (Hydroptic-6) which could sense the change of pressure added to the renal parenchyma in the parallel movement of the metal bar. The critical angle in regard to the deflection of the renal parenchyma in order not to cause the rupture of renal parenchyma on PNL was calculated from both the resultant force and the shape of the wound of renal parenchyma at rupture. The safety angle against horizontal plane of the tract ranged from 18 to 37 degree.