Prospective Outcomes of Ultra Mini Percutaneous Nephrolithotomy: A Consecutive Cohort Study.

PURPOSE: Ultra mini percutaneous nephrolithotomy is a less invasive technique of percutaneous nephrolithotomy to treat small to medium sized calculi. MATERIALS AND METHODS: We prospectively evaluated the outcomes of ultra mini percutaneous nephrolithotomy in a single surgeon, consecutive cohort study. Data on 94 patients who underwent ultra mini percutaneous nephrolithotomy were collected. RESULTS: Mean ± SD calculus size was 15.9 ± 4.5 mm and mean density was 1,106 ± 167 HU. Access was achieved via the upper pole in 8 cases, interpolar in 33 and lower pole in 54. Mean operative time was 54 minutes (range 28 to 120). Mean hemoglobin loss was 0.81 gm/dl and the mean creatinine increase was 0.05 mg/dl. There were no transfusions or kidney injuries. Grade I and IIIb complications were observed in 4 and 1 patients, respectively. The most serious complication was a perinephric collection. Postoperatively oral analgesia was sufficient in 86 patients (91%). Mean length of stay was 38.2 ± 15.9 hours. Nephrostomy drainage was used in 13 patients while 7 (7%) required a stent for 1 week. Intraoperatively 99% of renal units were stone free (absence of detectable calculi) on fluoroscopy, and 74% and 81% were stone free on day 1 postoperative ultrasound and 1-month computerized tomography, respectively. The 10 to 20 mm stones showed less bleeding, shorter operative time and a significantly lower requirement for nephrostomy or a Double-J(®) stent. CONCLUSIONS: Ultra mini percutaneous nephrolithotomy appears to be effective and safe with a short length of stay. It may be a valuable addition to the armamentarium to treat 10 to 20 mm calculi in patients who wish to avoid routine nephrostomy or stents. Randomized, controlled trials are required.

Ultra-mini percutaneous nephrolithotomy (UMP): one more armamentarium.

OBJECTIVE: To describe our newly developed technique for the removal of renal stones, which we have called ultra-mini percutaneous nephrolithotomy (UMP). METHODS: UMP was performed in 62 patients using a 3.5-F ultra-thin telescope and specially designed inner and outer sheaths. A standard puncture was made and the tract was dilated up to 13 F. The outer sheath was introduced into the pelvicalyceal system and the stone was disintegrated with a 365-µ holmium laser fibre, introduced through the inner sheath. Stone fragments were evacuated using the specially designed sheath by creating an eddy current of saline; the fragments then came out automatically. RESULTS: The mean calculus size was 16.8 mm. Four of the 62 patients were children, three had a solitary kidney and two were obese. UMP was feasible in all cases with a mean (SD) 1.4 (1.0) gm/dL haemoglobin decrease and a mean hospital stay of 1.2 (0.8) days. The stone-free rate at 1 month was 86.66%. In two patients intraoperative bleeding obscured vision, requiring conversion to mini-percutaneous nephrolithotomy. There was one postoperative complication of hydrothorax, but there were no other postoperative complications and no auxiliary procedures were required. CONCLUSIONS: UMP is a very safe and effective method of removing renal calculi up to 20 mm. The use of consumables and disposables is minimal and the patient recovery was fast. Further clinical studies and direct comparison with other available techniques are required to define the place of UMP in the treatment of low-bulk and medium-bulk renal urolithiasis. It may be particularly useful for lower calyx calculi and paediatric cases.