Fact-sheet: Retroaortic left renal vein


Updated on 07/01/2020 at 9:20 AM

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Definition

This is an anatomic position of the left renal vein observed in 1 to 3% of the general population.

This vein is in the anteaortic position in more than 95% of the general population.

Compression of the left renal vein between the superior mesenteric artery and the aorta is called Nutcracker Syndrome (NS).

Clinical features

This anatomic variant is most often asymptomatic.

Symptomatic compression of the left renal vein (Nutcracker syndrome) can induce various clinical manifestations:

  • asymptomatic microscopic hematuria, or macroscopic hematuria.
  • abdominal or left flank pain, sometimes accompanied by nausea or vomiting.
  • orthostatic proteinuria.
  • pelvic congestion syndrome due to reflux into the left gonadal vein
  • left varicocele with testicular pain in men.

CT

There are two types of NCS:

-> the most classic is anterior NCS, related to compression of the left renal vein between the SMA and the aorta

-> the other, rarer type, is posterior NCS, related to compression of the left renal vein between the aorta and the vertebral body when the left renal vein is retro-aortic.