User blog:Pionera/Vampires have blue blood veins?

Hey! I was recently re-listening to the first audiobook of the Twilight Saga: Twilight, and my mind suddenly picked out the words "the faint pattern of bluish veins inside the crease at his elbow". I am not sure at which page this is in the book, however, this is the first time in the book series that Edward brings Bella to the medow.

Now, I was under the impression, and do correct me if I'm wrong, that veins right under the skin appear blue due to the way light interacts with blood and skin. Doesn't that mean that Edward, a vampire, would have to have blood - not in his digestive system or whatever, but in his veins?