Prevalence of Congenital Anomalies of the Inferior Vena Cava: CT Assessment in Thai Patients

Objective: To determine the prevalence of inferior vena cava (IVC) anomalies in Thai patients who underwent contrast-enhanced computed tomography (CT) of the abdomen. Materials and Methods: Two radiologists retrospectively and independently reviewed the contrast-enhanced abdominal CT examinations in 1,429 Thai patients between August 1, 2018 and January 25, 2019 who met the inclusion criteria. Patients were included, if (a) their CT showed well visualized IVC, renal veins, and right ureter that were not obliterated by tumor, cyst, fluid collection, or intraperitoneal free fluid, (b) they had not undergone previous abdominal surgery that altered anatomical configuration of the IVC, renal veins, and right ureter. The presence of all IVC anomalies were recorded. Results: Among the 1,429 studied patients, 678 were male (47.4%) and 751 were female (52.6%). The prevalence of IVC anomalies was 3.5%. Five types of IVC anomalies were presented. The most common was circumaortic left renal vein in 24 patients or 48.0% of all IVC anomalies and 1.7% of the study population, followed by retroaortic left renal vein in 15 patients or 30.0 % of all IVC anomalies and 1.0% of the study population. Other IVC anomalies included double IVC, left IVC, and retrocaval ureter at 0.5%, 0.2%, and 0.1% of the study population, respectively. Conclusion: The prevalence of IVC anomalies in the present study differed from the previous studies conducted in other countries, which may be attributable to differences in race and ethnicity. Awareness of these anomalies is essential when evaluating routine CT examinations in asymptomatic patients. Their presence should be carefully noted in radiology reports to avoid anomaly-related complications. Keywords: Prevalence; IVC anomalies; Circumaortic left renal vein; Retroaortic left renal vein; Double IVC; Left IVC; Retrocaval ureter