[Pressure-flow study after percutaneous nephrolithotripsy].

In 46 patients treated with PNL in our hospital, the intervals from PNL to removal of a catheter indwelled in the nephrostomy were studied. The intervals were longer in the cases with ureteral stones than those with renal stones probably because of the different degrees of obstruction. To investigate the degree and the interval of upper urinary tract obstruction after PNL, Pressure-flow Studies were performed every or every other day after PNL in 5 cases with renal stones and 5 cases with ureteral stones, selected from 46 cases. In Pressure-flow Studies, intrapelvic pressures were measured while saline mixed with pigment was being dripping at a rate of 5 ml/min into the renal pelvis through the nephrostomy catheter. Saline initially reached into the urinary bladder at an average of 4.8 days after PNL (range 3 to 7 days) with a mean intrapelvic pressure of 37.6 cmH2O (range 28 to 52 cmH2O) in the cases with renal stones and at an average of 9.2 days (range 7 to 12 days) with a mean intrapelvic pressure of 27.0 cmH2O (range 9 to 43 cmH2O) in the cases with ureteral stones. Pressure-flow Studies were performed again a few days after the initial passage of saline into the urinary bladder in 2 of 10 cases. The intrapelvic pressures, 16 cmH2O and 13 cmH2O, respectively, several days after the initial passage of saline were lower than those, 35 cmH2O and 43 cmH2O, respectively, at the initial passage of saline. Therefore, it was likely that the proper interval of indwelling catheter after PNL was about 7 to 8 days, in the cases with renal stones and about 11 to 12 days in the cases with ureteral stones.