Renal Pelvis Urine Sampling for Microbiology in Patients Undergoing Ureteric Stent Insertion for Infected Obstructed Kidneys: A Departmental Practice Review for Compliance With Standard Care

TL;DR

This audit found that many patients with infected obstructed kidneys did not have proper urine sampling during stent insertion, affecting accurate microbiology results.

Contribution

The study evaluates compliance with RPU sampling standards and compares microbiology results from different urine and blood samples in IOK patients.

Findings

41% of patients did not have RPU sampled during stent insertion.

Microbiology concordance rates were 63% (RPU vs BUS), 67% (RPU vs blood), and 65% (BUS vs blood).

Kappa analysis showed fair to poor agreement between sample types, with the lowest agreement between BUS and blood.

Abstract

Introduction

Ureteric stent insertion allows the collection of renal pelvic urine (RPU) for microbiology, aiding targeted antibiotic use in infected obstructed kidneys (IOK). This retrospective audit reviewed compliance with European Association of Urology standards for RPU sampling, assessed whether urine dipstick tests and bladder urine samples (BUS) were obtained at initial evaluation, and compared microbiology results from BUS, RPU, and blood samples.

Methods

This retrospective audit reviewed patients with sepsis from suspected IOK who received emergency ureteric stents between October 1, 2024 and February 28, 2025. Microbiological outcomes were evaluated for concordance, and kappa analysis was used to measure agreement.

Results

Among the 51 patients undergoing ureteric stent insertion for IOK, fever was the main indication and obstructing ureteric stones were the most common cause of sepsis. Three quarters of patients lacked a dipstick urine test, and one-fifth had no BUS sent for microbiology at presentation. RPU sampling was not done in 41% of cases during stent insertion. Concordance rates for microbiology results were 63% (RPU vs BUS), 67% (RPU vs blood), and 65% (BUS vs blood). Kappa analysis found fair agreement between RPU and blood, poor agreement between RPU and BUS, and the lowest agreement between BUS and blood microbiology results.

Conclusion

The audit highlights a need to improve compliance with obtaining RPU samples for microbiology, which is vital for managing IOK-driven sepsis. Conducting larger audits in this area can offer more insights into microbial growth and antimicrobial sensitivity patterns.

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