Double inferior vena cava is formed due to?

Ans. is 'd' i.e., Persistance of both supracardinal and subcardinal veins Developmental anomalies of veins A. Anomalies of SVC Left superior vena cava is formed when left anterior cardinal and common cardinal veins persist and the right ones obliterate. Left SVC opens into right atrium through the coronary sinus. Double superior vena cava occurs due to persistence of left anterior cardinal vein. The right SVC opens directly into right atrium while left one opens through coronary sinus. B. Anomalies of IVC Absence of inferior vena cava above renal veins occurs when the anastomotic channel between right subcardinal vein and right lepatocardinal channel fails to develop. Double inferior vena cava is formed below renal veins due to persistence of both the subcardinal and supracardinal veins below the kidney. Left inferior vena cava, i.e. infrarenal pa of IVC is formed on left side instead of right. Preureteric IVC is formed when infrarenal pa of IVC develops from subcardinal vein (which lies anterior to ureter) instead of supracardinal vein (which lies posterior to ureter).