You've likely heard of medical tourism -- when individuals travel abroad to obtain health care they find too costly or delayed at home. What you might not realize is that this industry, fueled by inefficiencies in national health care systems and an increasingly interconnected world, is estimated to be worth tens of billions of dollars annually. In his new book, Outpatients: The Astonishing New World of Medical Tourism, journalist Sasha Issenberg takes a look at the practice and its ramifications for the way people around the world receive health care. He examines examples ranging from a Hungarian dentist who has built an empire out of treating travelers, to heart surgery on the cheap in Thailand, to a backlash against foreign patients in Israel.