Renal intrapelvic pressure during percutaneous nephrolithotomy and its correlation with the development of postoperative fever

Purpose: Systemic absorption of irrigation fluid containing bacteria or endotoxin may lead to fever and urosepsis after percutaneous nephrolithotomy. Although to our knowledge the exact method of absorption is undefined, intrapelvic pressure greater than 30 mm. Hg has been shown to result in pyelovenous-lymphatic backflow. We measured intrapelvic pressure during percutaneous nephrolithotomy and correlated pressure with postoperative fever and operative technique. Materials and Methods: Intrarenal pressure was measured with a transurethral 7Fr ureteral occlusion balloon catheter and a urodynamic system during percutaneous renal access, rigid and flexible nephroscopy, and intracorporeal lithotripsy. Postoperative fever was correlated with elevated intrarenal pressure, stone type and surgical technique. Results: Enrolled in this study were 18 women and 13 men. Pressure greater than 30 mm. Hg was recorded in 8 patients (26%). Elevated pressure occurred under 2 conditions, namely incomplete positioning of the nephroscopy sheath within the collecting system and endoscopy through a narrow infundibulum. In 13 cases (42%) a fever of 38C or greater developed postoperatively. Elevated pressure did not correlate with fever. However, of those undergoing percutaneous nephrolithotomy for the removal of infection versus noninfection stones 64% and 24%, respectively, had fever postoperatively. Conclusions: Renal intrapelvic pressure generally remains low during percutaneous nephrolithotomy. Elevated pressure was associated with incomplete nephroscopy sheath positioning within the collecting system and endoscopy through an infundibular narrowing. There was no association of renal pressure greater than 30 mm. Hg with fever but postoperative fever and percutaneous nephrolithotomy done for infection related stones correlated significantly.