Exceedingly rare incidence of a double inferior vena cava (IVC) with azygos continuation of left IVC

Abstract

Key Clinical MessageBecause of the complex embryonic origin of the abdominal venous structures, IVC and azygous systems can show numerous and even previously unreported anatomical variations and anomalies. Also, evaluating major vascular structures should not be dismissed in non‐contrast‐enhanced CT as it can provide valuable information about these structures.AbstractDouble IVC is a rare occurrence of IVC anatomical variations and congenital anomalies. Herein, we discuss a case of a very rare type of double IVC that has not been reported in the literature before. A non‐contrast‐enhanced CT study was performed for a 34‐year‐old patient who visited our ER to evaluate for urolithiasis, during which two IVCs were noted. Each renal vein joined the ipsilateral IVC at a perpendicular angle. Unusually, the right IVC was formed from the confluence of both left and right common iliac veins (CIV), and the left IVC—Instead of crossing the midline at the renal veins level and reuniting the right IVC—cranially contributed to the azygos vein formation and caudally joined the left CIV. Also, there were some small communicating veins between the two IVCs and the left gonadal vein was slightly dilated before suggesting a reflux from the left renal vein (LRV). A complimentary doppler ultrasound exam confirmed the diagnosis and revealed a left‐side varicocele. Although rare cases of hemiazygos continuation and interiliac connections of left‐side IVC in the cases of double‐IVC have been reported previously, a complete confluence of CIVs is rare. The main differential diagnosis is retro‐aortic left renal vein (RLRV) type IV which seems to have an oblique course. Radiologists and surgeons should expect previously unreported variations in the vena cava system. Furthermore, reviewing the main abdominal vasculature should not be dismissed in non‐contrast CT exams.