Clinical History
62-year-old male patient was referred for a CT chest and abdomen to rule out malignancy because of unintentional weight loss and high ESR. This was the first time he was being scanned.
Imaging Findings
A contrast-enhanced CT chest and abdomen with intravenous contrast in portal venous phase was performed to rule out malignancy. As an incidental finding a left-sided inferior vena cava was found, which crossed over the aorta anteriorly to the right side at the level of renal veins. No other vascular abnormality was found.
Discussion
Background:
Transposition of inferior vena cava (IVC), also known as left-sided IVC, refers to a variant course of the IVC, occurring due to persistence of left supracardinal vein in 0.2-0.5% of the population with or without other cardiovascular defects, making it the most common anomaly of IVC. [1, 2, 3] The embryogenesis of the IVC is a complex process involving development and regression of the three paired embryonic veins. A left IVC typically empties in the left renal vein, which crosses anterior to the aorta to form a normal right-sided pre-renal IVC, but it can also take a retro-aortic course and is usually associated with multiple renal veins. [2, 3] Other possible anomalies are: Double IVC, azygos continuation of the IVC, circumaortic left renal vein, double IVC with retro-aortic right renal vein and hemiazygos continuation of the IVC, double IVC with retro-aortic left renal vein and azygos continuation of the IVC, circumcaval ureter, absent infrarenal IVC with preservation of the suprarenal segment. [2, 3]
Clinical perspective:
Such anomalies are usually asymptomatic but incidentally diagnosed with CT, MR or during abdominal surgery. [1] It is crucial to diagnose it preoperatively to avoid iatrogenic injury or inadvertent ligation particularly before vascular procedures like portosystemic shunts, abdominal aortic aneurysm repair, ligation of IVC in thromboembolic disease, placement of IVC filter, nephrectomy and renal transplantation. Familiarity with the variant anatomy can assist surgeons in laparoscopic and robotic surgeries where a narrow field of view makes it extremely difficult to appreciate aberrant venous anatomy. [1]
Imaging Perspective:
Congenital abnormalities of IVC are easily identified on CT and should be considered when interpreting any CT of the abdomen or chest. [1] It can be misdiagnosed as left-sided para-aortic adenopathy, retro-peritoneal or mediastinal masses where MR should be considered to distinguish the masses by demonstrating flow voids or flow-related enhancement. [2]
Outcome:
Correct interpretation of IVC anomalies can save surgeons from disastrous consequences as they can plan surgical management accordingly.
Teaching Points:
Anomalies of IVC are extremely rare but it is essential to be aware of them and report to surgeons especially in the planning of vascular procedures to prevent severe vascular complications and to avoid diagnostic pitfalls.
Differential Diagnosis List
Transposition of inferior vena cava
Left-sided para-aortic adenopathy
Retro-peritoneal mass
Mediastinal masses
Final Diagnosis
Transposition of inferior vena cava
