Anomalies of the Inferior Vena Cava and Their Clinical Significance

1. Left IVC: joins the left renal vein and crosses anterior to the aorta to join the right renal vein

• can be mistaken for paraaortic adenopathy
• report of AAA rupture into the IVC

2. Double IVC: the left IVC ends at the level of the left renal vein which crosses anterior to the aorta to join the confluence of the right IVC/renal vein.

• suspect if patient has recurrent pulmonary embolism after placement of an IVC filter

3. Azygous continuation of the IVC: above the renal veins the IVC passes posterior to the diaphragmatic crus and continues as the azygous vein which joins the superior vena cava in the right paratracheal region. The hepatic segment of the IVC empties directly into the right atrium.

• important to consider in cases of a right paratracheal mass 
• can be mistaken for retrocrural adenopathy

4. Circumaortic left renal vein: two left renal veins are present; the superior renal vein receives the left adrenal vein while the inferior renal vein receives the left gonadal vein.

• significant during planning of nephrectomy

5. Retroaortic left renal vein: a single left renal vein passes posterior to the aorta

• recognition during preoperative planning is important

6. Double IVC with retroaaortic right renal vein and hemiazygous continuation of the IVC: confluence of the right renal vein and right IVC crosses posterior to the aorta to join the left IVC and continue cephlad as the hemiazygous vein. Several collateral pathways for the hemiazygous vein exist in the thorax - hemiazygous crossing posterior to the aorta to join the azygous vein, hemiazygous joining the cardinal vein of the heart via a persistent left SVC, and accessory hemiazygous continuation to the brachocephalic vein

• hemiazygous collateral pathway may be mistaken for a left mediastinal mass
• accessory hemiazygous has been reported to be mistaken for an aortic dissection

7. Circumcaval ureter: always occurring on the right, the proximal ureter courses posterior to the IVC and emerges to the right of the aorta and continues anterior to the right iliac vessels.

• patients may develop partial ureteral obstruction or recurrent urinary tract infections
• treatment is surgical relocation of the ureter anterior to the IVC

8. Absent infrarenal IVC with preservation of the suprarenal segment: external and internal iliac veins converge as lumbar veins which continue cephlad as the paravertebral collateral veins to join the azygous and hemiazygous. The confluence of the renal veins forms a normal suprarenal IVC.

• patients may present with symptoms of lower extremity venous insufficiency or idiopathic deep venous thrombosis
• collateral circulation may mimic a paraspinal mass

REFERENCES

Bass JE, Redwine MD, Kramer LA, et al. Spectrum of congenital anomalies of the inferior vena cava: cross-sectional imaging findings. Radiographics. 2000 May;20:639-52.