Spontaneous urinary extravasation: detection rate with 64-row multidetector computed tomography in patients presenting with acute abdomen

Spontaneous Ureteral Urine Extravasation From Invasion of a High-grade Angiosarcoma

A 69 year-old male with a past medical history of hypertension, diabetes, and atrial fibrillation presented to the Urology clinic with asymptomatic microscopic hematuria. His work up for hematuria included a negative cystoscopy and a computed tomography (CT) scan, which revealed what appeared to be a fluid collection around the left kidney with a perinephric infiltrative mass and two para-aortic enlarged lymph nodes.

The relative contribution of urine extravasation to elevate plasma creatinine levels in acute unilateral ureteral obstruction

INTRODUCTION

Rising levels of plasma creatinine in the setting of acute unilateral ureteral obstruction (AUUO) often reflects acute renal failure, mandating kidney drainage. We hypothesize that re-absorption of peri-renal urine extravasation (PUE), a common result of UUO, contributes significantly to the elevation in plasma creatinine, rendering the latter an inaccurate benchmark for renal function. We explored this hypothesis in a rat model of AUUO and PUE.

METHODS

In total, 20 rats were equally divided into 4 groups. Groups 1 and 2 underwent unilateral ligation of the ureter with infiltration of rat's urine (index group) or saline (control) into the peri-renal space. Two additional control groups underwent peri-renal injection of either urine or saline without AUUO. Plasma creatinine levels were determined immediately prior to the procedure (T0), and hourly for 3 hours (T1, T2 and T3). Renal histology was investigated after 3 hours.

RESULTS

Rats in the index group had a significantly greater increase in plasma creatinine levels over 3 hours compared to all other groups (p < 0.05). At T3, average plasma creatinine levels for the index group increased by 96% (0.49 ± 0.18 mg/dL) compared to 46% (0.23 ± 0.06 mg/dL increase) in the AUUO and saline group, and less than 15% rise in both the non-obstructed control groups. Our study limitations includes lack of spontaneous PUE and intraperitoneal surgical approach.

CONCLUSIONS

Absorption of peri-renal urine in the presence of AUUO is a significant contributor to rising plasma creatinine levels, beyond those attributable to the obstruction alone, and may overestimate the extent of the true renal functional impairment.