There is a bundle of varicose veins (arising from the left testicular vein) medial to the left kidney. When tracing the left renal vein along its course to the vena cava, you will find the vein markedly compressed when passing between the superior mesenteric artery and the aorta.
As incidental findings, this patient also turned out to have two accessory spleens, as well as a duplex left collecting system fusing at the pelviureteric junction.