Pitfalls in the detection of urinary extravasation following major urinary tract reconstructive surgery

Urinary extravasation may complicate the postoperative course of urinary tract reconstructive surgery. Early diagnosis of extravasation is critical in the postoperative management. In this study we assessed prospectively the various diagnostic techniques employed in the detection and documentation of urinary extravasation in 76 consecutive patients who underwent major urinary tract reconstructive surgery. Assessment included measurements of the volume of the fluid obtained from the drains, analysis of serum to fluid creatinine ratio, detection of intravenously injected indigo dye and traditional radiographic evaluation. Urinary extravasation was detected in 7 patients (9.2%). Increased creatinine ratio had the highest diagnostic accuracy: 97.3%, sensitivity 71.4% and specificity 100%. Various radiological investigations had accuracy of 96%, sensitivity 85.7% and specificity 97.1%. The combined use of these methods detected all cases of urinary extravasation with sensitivity, specificity and total accuracy of 100%. Fluctuations in the volume of fluid in the drains and intravenous injection of indigo dye had lower accuracy, sensitivity and specificity and added very little to the workup. We conclude that radiological investigations and creatinine ratio analysis are highly accurate complementary methods for the early detection and monitoring of urinary extravasation following reconstructive urinary tract surgery.