Creation of an end-to-end anastomosis is a basic microsurgical skill that is taught to surgical residents and fellows.
As warm arterial blood passes close to the surface it will decrease in temperature.
[citation needed] Pathological circulatory anastomoses result from trauma or disease and may involve veins, or arteries.
Portacaval anastomosis, by contrast, is a veno-venous anastomosis between a vein of the portal circulation and a vein of the systemic circulation, which allows blood to bypass the liver in patients with portal hypertension, often resulting in hemorrhoids, esophageal varices, or caput medusae.
Circulatory anastomoses between monochorionic twins may result in twin-to-twin transfusion syndrome.