Why do i suddenly have blue veins on my breasts?

Venous congestion: Anything that affect the venous drainage from an organ can cause the veins to become engorged (i.e. Filled with blood) and more visible.

Normal finding: I am amazed about how often I have women ask me about the veins on their breast. Occasionally they are spider veins but mostly they are blue veins. These are almost always normal findings and normal variations of chest veins. They tend to be more pronounced in fair skinned females and they may be related to hereditary factors or even pregnancies. No treatment is necessary unless for cosmetics.