The nutcracker phenomenon (NCP) is an accentuated phenomenon of normal subtle compression of the left renal vein (LRV) between the abdominal aorta and superior mesenteric artery. The nutcracker syndrome (NCS) is a syndrome caused by NCP, resulting in hematuria, proteinuria, or left flank pain.  

The established diagnostic criterion of NCP is a pressure gradient more than 3 mmHG across the compression site, and NCS has been known to be rare, but probably is not rare and in fact quite common. The most important reason why NCS is known to be rare is that the diagnosis is...