In medicine, portal anastomosis is considered as an alternative route of the blood circulation, which enables the Blood to bleed off to the vena cava inferior, if the vena portae hepatis is blocked. Such an anastomosis occurs between the veins of portal circulation and those of systemic circulation. A congestion of the vena portae (caused for example by cirrhosis of the liver) hepatis can cause a portal hypertension. Blood flowes directly to the vena cava by portalcaval anastomosis. However, the capacity of this „alternative route“ is very limited! Thus, because of the increased blood flow, some clinical syndroms can happen (for example varices occur, a caput medusae or an enhanced appearence of veins at the region of the umbilicus). In addition, some varices can be created inside the esophagus. This can be very dangerous because the varices can lead to very serious bleedings if they are damaged.
The following „alternataive routes“ count to the portocaval anastomosis:
Vena portae hepatis → Venae gastricae → Venae oesophageales → Vena azygos/hemiazygos → Vena cava superior
Vena portae hepatis → Venae paraumbilicales → Vena epigastrica superior → Vena thoracica interna → Vena brachiocephalica → Vena cava superior
Vena portae hepatis → Venae paraumbilicales → Vena epigastrica inferior → Vena iliaca externa → Vena cava inferior
Vena portae hepatis → Vena mesenterica superior/inferior → Venae colicae → Venae lumbales ascendentes → Vena azygos/hemiazygos → Vena cava superior
Vena portae hepatis → Vena mesenterica inferior → Vena colica sinistra → Vena testicularis/ovarica sinistra → Vena renalis sinistra → Vena cava inferior
Vena portae hepatis → Vena mesenterica inferior → Vena rectalis superior → Vena rectalis media/inferior → Vena iliaca interna → Vena cava inferior