Residual air persists in the renal collecting system following percutaneous nephrolithotomy

Objectives: To determine the presence or absence of air in the renal collecting system 48 hours following percutaneous nephrolithotomy (PCNL). Methods: The study was based on a review of the records of the last 100 consecutive patients undergoing PCNL for stone extraction. Two urologists and a uroradiologist reviewed post-PCNL nephrostogram films and determined the presence or absence of air in the urinary tract. Results: Nephrostography was routinely performed 48 hours after PCNL, and all films of the 100 patients were reviewed. Gas was detected in 98 (98%) of the 100 cases that appeared as gas pyelograms outlining the renal calyces. Of the 98 cases, 33 (34%) demonstrated gas in the upper calyx, 10 (10%) in the middle calyx, 12 (13%) in the lower calyx, and 43 (44%) in more than one calyx. Gas was not detected in the renal parenchyma or perirenal areas. Conclusions: Gas is present within the renal collecting system 48 hours after a percutaneous procedure. Prospective studies should be performed to document the amount of time needed for complete resolution of gas from the collecting system.