Background: Ultra-mini PCNL (UMP) is a device that removes stones by using 7.5 Fr. nephroscope and 11/12 Fr. working sheath. The stone free rate (SFR) does not lag behind the convetional PCNL, but due to the diameter of the small device, UMP has many disadvantages; Irrigation pressure increases easily during surgery and post operative febrile urinary tract infection (UTI) is relative common. The purpose of this study is to present the surgical results of UMP with strict irrigation pressure control using a pressure control irrigator.
Methods: 70 consecutive patients who underwent UMP surgery for kidney stones were enrolled retrospectively. All surgeries proceeded with the shoulder rotated supine position. Of these, initial 35 patients underwent surgery using 100 mmHg irrigation power previously and later 35 patients underwent surgery below 40 mmHg irrigation power.
Results: The stone size of the UMP 100 mmHg group was 2.52 ± 1.05 and that of the UMP 40 mmHg group was 2.79 ± 1.32 respectively. Operative time was also slightly shorter in the UMP 40 mmHg group, but there was no statistical difference between the two groups. There was no statistical difference in stone free rate, but UMP 100 mmHg group showed 37.1% of post operative febrile urinary tract infection rate and 11.4 % in UMP 40 mmHg group and they are significantly different (p = 0.039).
Conclusions: Strict irrigation pressure control below 40 mm during UMP can reduce post operative febrile UTI without affecting SFR.
Keywords: intra-renal pressure; irrigation pressure; ultra-mini percutaneous nephrolithotomy; urinary tract infection.