Imaging Case of the Week 147

The following KUB plain x-rays are from a 50 year old with acute left flank pain, fever and vomiting.

 

Xray KUB 1Xray KUB 2

 

What can be seen on the x-ray which, along with clinical features, makes it a concerning urological presentation?

What incidental finding can also observed on the x-ray that can present as a vascular emergency?