# Utility of the Drain Fluid-to-Serum Creatinine Ratio for Diagnosing Postoperative Complications Following Genitourinary Surgery in Moroccan Patients

## TL;DR

This study shows that a simple blood and fluid test can accurately detect urinary leakage after genitourinary surgery in Moroccan patients.

## Contribution

The study validates the diagnostic accuracy of the drain fluid-to-serum creatinine ratio for postoperative urinary leakage in a Moroccan cohort.

## Key findings

- The DCr/PCr ratio was significantly higher in patients with urinary leakage (22.48) compared to those without (1.63).
- A cutoff of ≥4.0 achieved 86.7% sensitivity and 97.1% specificity for detecting leakage.
- The diagnostic accuracy (AUC of 0.977) suggests the DCr/PCr ratio is a reliable tool for postoperative monitoring.

## Abstract

Background: Postoperative complications represent a major challenge in genitourinary surgery. The drain fluid-to-plasma (serum) creatinine (DCr/PCr) ratio has emerged as a simple, cost-effective biochemical marker for detecting postoperative urinary leakage.

Objective: To evaluate the diagnostic performance of the DCr/PCr ratio in identifying postoperative urinary leakage in a Moroccan patient cohort.

Methods: A retrospective study was conducted on 118 patients who underwent genitourinary surgery between May 2022 and April 2024. Simultaneous serum and drain fluid creatinine measurements, performed during the first postoperative days, were analyzed alongside clinical and demographic data.

Results: The cohort had a mean age of 65.36 years and was predominantly male (95.8%). Laparoscopic radical prostatectomy (51.7%) and radical cystectomy with urinary diversion (22.9%) were the most common procedures. The mean DCr/PCr ratio was markedly higher in patients with urinary leakage (22.48) than in those without leakage (1.63). ROC curve analysis demonstrated excellent diagnostic accuracy, with an area under the curve (AUC) of 0.977 (95% CI: 0.949-0.996). A cutoff value of ≥4.0 yielded a sensitivity of 86.7%, specificity of 97.1%, and a negative predictive value of 98.0%.

Conclusion: The DCr/PCr ratio is a highly accurate, rapid, and cost-effective tool for detecting postoperative urinary leakage. A cutoff of ≥4.0 provides excellent diagnostic performance, particularly for ruling out leakage. Routine integration of this biochemical marker into postoperative assessment protocols may improve early detection and reduce unnecessary imaging, although prospective multicenter validation remains warranted.