Teaching Case

A 53-year-old woman, with a clinical history of cervical cancer under chemotherapy, benefited from a thoraco-abdomino-pelvic CT for the evaluation of response to treatment.

Besides the radiological anomalies for which she was followed-up, we have incidentally found a retro-aortic left renal vein joining the Inferior Vena Cava in the orthotopic position at the level of L4-L5 vertebras.

Variant anatomy of arteries and veins are seen more commonly in abdomen than in any other part of the body [1].
A recognition of variations represented by renal and suprarenal veins is important in study and treatment of renal transplantation, renal trauma, renovascular aneurysm and renal surgery [2–4].
A retroaortic left renal vein (RLRV) is a vein passing behind the abdominal aorta, and this anomaly is relatively rare [5].
Left renal vein (LRV) abnormalities were divided into four types [6, 7]:
Type I: the RLRV joins the inferior veina cava (IVC) in the orthotopic position.
Type II: it joins the IVC at level L4-5.
Type III: it joins at the circumaortic or collar left renal vein.
Type IV: it joins the left common iliac vein.
The incidences of RLRV type I, II, III and IV are 0.3-1.9%, 0.4-0.9%, 1.5-8.7% and 0.16%, respectively [5].
Embryologically, the anterior part of the circumaortic venous plexus continues to exist as a normal LRV. The absence of the anterior part with persistence of posterior component leads to the formation of RLRV [8].
RLRV may sometimes cause symptoms such as haematuria and abdominal or flank pain [9].
Radiological modalities (Colour Doppler US, angiography, MRI and CT) can be used to explore LRV.
MDCT has replaced conventional angiography and venography in most cases; it is a reliable, easily applicable, and noninvasive means for exploration of abdominal organs and vascular structures [5].
Type II is due to the obliteration of the ventral preaortic limb of the LRV, and the remaining dorsal limb becomes the RLRV. The LRV lies at the level of L4 to L5 and joins the gonadal and ascending lumbar veins before joining the IVC [5].
It is supposed that the compression of the LRV leads to haematuria because of elevated pressure in this vein, engendering congestion of the left kidney and the venous communications [5].
Diagnosis of renal vein anomalies is important in retroperitoneal surgery; the ignorance of this variant can result in bleeding, nephrectomy, and even death [10].
Surgeons prefer the LRV in renal transplantation because of its length. So, it is important to notice the route of the LRV and whether it is pre-aortic or not.

Before the renal surgery, attentive reading of the preoperative RLRV imaging modalities helps to prevent fatal complications during the operation.