Does percutaneous nephrolithotomy and its outcomes have an impact on renal function? Quantitative analysis using SPECT-CT DMSA

Mini percutaneous nephrostolithotomy was developed for use in children and in adults with a reduced renal reserve to minimize the morbidity and renal parenchymal damage presumed to occur with traditional percutaneous nephrostolithotomy. We compared the extent of renal injury incurred by different sized nephrostomy tracts in female farm pigs undergoing 11 or 30Fr percutaneous nephrostomy. Bilateral percutaneous nephrostomy was attempted via a mid or lower pole calix under fluoroscopic guidance in 6 pigs. In 2 pigs the procedure was unsuccessful on 1 side, leaving 5 successfully established nephrostomy tracts on each side. In each pig the right percutaneous tract was dilated with a 28Fr dilating balloon and a 30Fr Amplatz working sheath (Cook Urological, Spencer, Indiana) was positioned in the collecting system. On the left side an 11Fr sheath (Cook Urological) was placed. The sheaths were removed after 1 hour and nephrostomy tubes (22Fr on the right and 8Fr on the left side) were left in place overnight and then removed. Six weeks later the pigs were sacrificed and the kidneys were harvested. The nephrostomy tracts were identified grossly and examined microscopically, and the fibrotic scar was measured using digital analysis. The volume of scar was estimated using the calculated volume of a cylinder. At kidney harvest all 10 kidneys appeared grossly normal. No intra-abdominal urine collection or perirenal hematoma was noted. Mean estimated scar volume of the 30 and 11Fr tracts was 0.29 and 0.40 cc, which translates into a mean fractional loss of parenchyma of 0.63% and 0.91%, respectively (p not significant). Renal parenchymal damage resulting from the creation of a nephrostomy tract is small compared to overall renal volume regardless of the size of the nephrostomy tract. Consequently there is no advantage to the use of a small access sheath based on renal scarring alone.

We report our experience with percutaneous nephrolithotomy (PCNL) in children, and evaluate its early and late anatomical and functional results. A total of 65 children with renal calculi were treated with PCNL. Patient age at operation ranged from 9 months to 16 years (mean +/- SD of 5.9 +/- 0.9 years), and 27 (41.5%) were younger than 5 years. Seven patients had bilateral renal stones and, therefore, the number of kidneys treated by PCNL was 72. The patients were followed regularly every 3 months during year 1 and every 6 months thereafter. Renal scans using technetium dimercapto-succinic acid for detection of renal scarring and technetium diethylenetetramine-pentaacetic acid for determination of selective glomerular filtration rate (GFR) were performed in all patients at least once during followup, which ranged from 6 to 72 months (mean +/- SD 40 +/- 10). Early complications included significant intraoperative bleeding in 1 case, renal pelvis perforation in 1 and transient fever in 2. Mean hospital stay +/- SD was 3 +/- 1.2 days (range 2 to 21). Of the renal units 62 (86%) were stone-free after a single PCNL, and the remaining 10 with residual stones were treated with a second look PCNL (4) and shock wave lithotripsy (6). Stone-free rates at hospital discharge and at 3 months were 93% and 100%, respectively. During followup 6 patients (9%) had recurrence of small renal stones and were successfully treated with shock wave lithotripsy. None of the kidneys had scarring on dimercapto-succinic acid renal scan. All of the kidneys except 1 showed improvement or stabilization of the corresponding GFR determined by diethylenetetraminepentaacetic acid renal scan. Comparison of the mean preoperative GFR of the corresponding kidney (28.8 +/- 11.2 ml per minute) with mean value at followup (36.1 +/- 9.9) showed an increase of statistical significance (p <0.01). PCNL is a safe and effective procedure for the treatment of children with renal calculi. At long-term followup the procedure improves renal function without renal scarring.

To compare the effects of one-stage vs gradual dilation techniques during percutaneous nephrolithotomy (PCNL) on postoperative renal scar formation and overall renal function.