<unk><unk>  of the IVC is AKA absence of the hepatic segment of the IVC with<unk><unk> .
The renal portion of the IVC receives blood return from both kidneys and passes posterior to the diaphragmatic crura to enter the thorax as the<unk>  vein.
The<unk>  vein joins the superior vena cava at the normal location in the right paratracheal space.
The hepatic segment (often termed the posthepatic segment) is ordinarily not truly absent; rather, it drains directly into the right atrium.
Each gonadal vein drains to the ipsilateral renal vein.
Formerly thought to be predominantly associated with severe congenital heart disease and asplenia or polysplenia syndromes,<unk><unk>  of the IVC has become increasingly recognized in otherwise asymptomatic patients since the advent of cross-sectional imaging.
It is important to recognize the enlarged<unk>  vein at the confluence with the superior vena cava and in the retrocrural space to avoid misdiagnosis as a right-sided paratracheal mass or retrocrural adenopathy.
Preoperative knowledge of the anatomy may be important in planning cardiopulmonary bypass and to avoid difficulties in catheterizing the heart.
Azygous continuation of the inferior vena cava
Coronary artery trifurcation
Coronary artery bifurcation
Valve of the inferior vena cava
Aortic intramural hematoma
Double inferior vena cava
Persistent left inferior vena cava
Retroaortic left renal vein