Ultrasound examination by urologist showed bilateral hydronephrosis leading to a request for nephrostomy placement by interventional radiologist on one side followed by the contralateral side 2 days later.

Follow-up CT showed an obstructing mass surround the aorta, which was not displaced anteriorly by the mass. Together with possible medialisation of the ureters due to traction this is typical of retroperitoneal fibrosis.