Clinical Report: Utility of Urine Culture During Stone Fragmentation in PCNL and RIRS

Overview

This prospective study evaluated the detection of bacteria in irrigation fluid during stone fragmentation in patients undergoing PCNL and RIRS. It assessed the concordance between bladder, renal pelvic, stone, and fragmentation urine cultures and their association with postoperative infectious complications such as SIRS.

Background

Infections are common complications following endourological procedures for urolithiasis, with significant rates of fever, SIRS, and sepsis reported after PCNL and RIRS. Preoperative bladder urine culture (BUC) and perioperative antibiotic prophylaxis are recommended to prevent infections, but BUC may not accurately reflect upper urinary tract microbiology. Stone and renal pelvic urine cultures have shown better predictive value for postoperative infections. Bacterial colonization of stones, endotoxin release during lithotripsy, and increased intrarenal pressure are potential mechanisms contributing to infectious complications.

Data Highlights

The study included adult patients undergoing PCNL and RIRS, with preoperative BUC and intraoperative sampling of renal pelvic urine, irrigation fluid during stone fragmentation, and stone cultures. Positive culture thresholds were ≥10^5 CFU/mL for BUC and ≥10^3 CFU/mL for other samples. Infectious complications were defined by SIRS criteria and classified per Clavien–Dindo. Antibiotic prophylaxis was tailored based on culture results.

Key Findings

• BUC often fails to predict postoperative infections due to lack of representation of upper tract microbiology.
• Stone and renal pelvic urine cultures are more accurate predictors of postoperative infectious complications than BUC.
• Bacteria can be released into irrigation fluid during stone fragmentation, potentially disseminating colonizing pathogens.
• Concordance between SFUC, RPUC, SC, and BUC varies, with SFUC providing additional microbiological information during surgery.
• Positive intraoperative cultures correlate with increased risk of postoperative SIRS and guide targeted antibiotic therapy.
• Use of a non-pressurized irrigation system and holmium:YAG laser fiber for lithotripsy are standard procedural aspects.

Clinical Implications

Routine intraoperative urine culture during stone fragmentation may improve detection of bacterial colonization and help tailor postoperative antibiotic therapy, potentially reducing infectious complications. Reliance solely on preoperative bladder cultures may underestimate infection risk. Incorporating renal pelvic and stone cultures into clinical practice can enhance infection risk stratification and management.

Conclusion

Intraoperative urine culture during stone fragmentation provides valuable microbiological data that complements preoperative bladder cultures and better predicts postoperative infectious complications in PCNL and RIRS. This approach supports more precise antibiotic stewardship and improved patient outcomes.

References

1. European Association of Urology Guidelines on Urolithiasis 2020 -- Prevention of Infectious Complications
2. Clinical Studies on Infectious Complications Post-PCNL and RIRS
3. Microbiological Techniques and Culture Thresholds in Urolithiasis Surgery