1680 ENDOSCOPIC-GUIDED PERCUTANEOUS NEPHROLITHOTOMY: A TECHNIQUE TO REDUCE RADIATION DOSAGE

tients (10 male). Eleven cases (11/19, 58%) were right sided. Mean BMI was 28.7 (SD 6). PCNL fluoro time for UARN was mean 2 min 1 s (n 16, SD 63.2 s) and mean* PCNL fluoro time in literature for antegrade access by urologist was 7 min 16s (SD** 9 min 24 s) (n 821 cases in 8 papers, p 001). Fluoro time for IR obtained antegrade nephrostomy for stone surgery at DMC was 16 min 42s (SD 19 min 45 s; n 12: 6 with hydro, 2 with stone in calyx, 4 with no hydro). UARN nephrostomy creation fluoro time for cases #3 and #9 was mean 3 min 36 s. Our UARN technique was developed during cases #1-9 (Figure 1) for which separate fluoro time for nephrostomy creation was not recorded. In cases #3 and #9, the access tracts were not dilated due to concern re: adjacent organs, after which pre-op CT scan review was initiated. After the UARN procedure was defined (after case #9), fluoro time for nephrostomy creation was mean 29.6 s (n 7, SD 29.8 s). UARN case data: Average stone size 11.4 cm2 (SD 9), mean 1.5 stones. Twelve cases (12/17, 71%) had no or min. hydronephrosis. Nephrostomy exit: 4 (24%) upper pole, 9 (53%) mid-pole, 4 (24%) lower pole. In 15 cases the nephrostomy exited a stone-bearing calyx; laser was employed to access calyx in 6 cases. Total PCNL time was mean 170 minutes (n 16). All cases were successful with no nephrostomyrelated complications. * Weighted average of the reported means ** Square root of the weighted sum of the literature variances CONCLUSIONS: Ureteroscopy-assisted retrograde nephrostomy offers a significant reduction in radiation exposure in the setting of PCNL compared to antegrade nephrostomy access obtained by urologist or interventional radiologist.