Nontraumatic Paraureteral Urinoma in a Cat with Urolithiasis.

Urinoma is an encapsulated collection of urine due to a disruption in the collection system of the urinary tract. This condition is rarely reported in veterinary medicine. The aim of this study is to describe the clinical and diagnostic findings of a well-encapsulated paraureteral urinoma associated with urinary tract stones in a critical feline patient. The ultrasound examination of the abdomen revealed a well-defined collection of anechoic fluid containing the left kidney in the retroperitoneal space, while the radiographic examination revealed a loss of soft tissue contrast in the lumbar region. Both techniques confirmed the presence of stones in the bladder. Following the ultrasound-guided drainage of the lesion, the nature of the fluid was also confirmed to be urine. Due to the worsening of the cat's health, to better define the extent and genesis of the lesion, a positive contrast radiographic study was performed by means of an ultrasound-guided percutaneous injection of a contrast medium into the lesion, which highlighted a wide and homogeneous radiopaque area in the left retroperitoneal space. These findings were confirmed with a postmortem examination, corroborating the diagnostic suspicion of urinoma. The percutaneous contrast inoculation performed in this critically ill patient plays a role in the diagnostic process to reach a final diagnosis in cases in which the patient's clinical condition does not allow for performing an excretory positive contrast study.