Fenestrated Common Iliac Vein – A Lesser-Known Congenital Anomaly of the Venous System

In the article titled “Developmental Anomalies of the Inferior Vena Cava and Its Tributaries: What the Radiologist Needs to Know?”, various developmental anomalies of the inferior vena cava (IVC) and its tributaries were discussed; however, no mention was made of anomalies involving the common iliac veins (CIV). In our practice, we encountered a rare case of a fenestrated right-sided CIV associated with a persistent isolated left-sided IVC. In this case, the two fenestrated channels of the right CIV united distally and joined the left CIV to form the IVC ([ Figs. 1 ] and [ 2 ]). Embryologically, this anomaly is attributed to the persistence of the left supracardinal vein, regression of the right supracardinal vein, and persistence of an anomalous right posterior cardinal vein. Additionally, a high aortic bifurcation with an anomalous retro-psoas right common iliac artery was noted. Fig. 1 ( A ) Coronal contrast-enhanced venous phase image showing a left-sided IVC ( white arrow ), fenestrated ( blue arrow ) distal right CIV ( red arrow ), and high bifurcation of the aorta ( yellow arrow ). ( B ) Coronal contrast-enhanced venous phase image showing the proximal course of the right CIV ( white arrow ; single lumen) with a fenestrated distal segment ( red arrow ). CIV, common iliac veins. Fig. 2 Coronal three-dimensional reformatted image demonstrating the left-sided IVC ( white arrow ), fenestrated distal right CIV ( red arrow ), the point of fenestration ( blue arrow ), and a non-dividing retro-psoas right common iliac artery. CIV, common iliac veins; IVC, inferior vena cava. Concurrent IVC and CIV anomalies constitute approximately 2% of all venous anomalies, with fenestrations accounting for less than 0.5% of cases.[ 1 ] [ 2 ] This anatomical variation may predispose patients to deep venous thrombosis. Failure to recognize these anomalies could prove catastrophic during abdominal surgery or interventional procedures such as intravenous catheterization.[ 2 ] Therefore, careful evaluation of the CIVs is recommended in patients with identified IVC anomalies. Publication History Article published online: 06 July 2026 © 2026. Indian Radiological Association. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/) Thieme Medical and Scientific Publishers Private Limited A-13A, Graphix Tower 1, 6th floor, Sector 62, Noida 201309, Uttar Pradesh, India