L04 - Stomach
4. Define and identify examples of portal-caval (systemic) anastomoses.
Portal-caval (systemic) anastomoses are areas where vessels of the portal venous & systemic venous systems communicate, allowing blood to still drain through one system (typically caval) if there is obstruction/diminished flow/increased pressure in the other (typically portal). These anastomoses are of particular importance in cases of portal hypertension (increased pressure in portal venous system). In more severe cases, an artificial communication (e.g. shunt) may need to be produced to allow drainage, and larger veins are typically used to allow more flow, such as the splenic v. (portal) and L. renal v. (caval).
There are four main naturally occurring portal-caval anastomoses:
- Inferior esophageal submucosa
- Peri-umbilical region
- Posterior portions of many secondarily retroperitoneal organs
- Inferior rectal/anal canal submucosa