I wouldn't do it. To me it means you're not yet sure of what specialty you want, and in that case I think you're better off taking more time to figure it out so when you do specialize, it's in the right field for you. Otherwise you could dedicate several years of your life to fellowship training only to find you wish you were in a different field after all. Better to take a year or two and decide what you really want. You can always work for awhile as a hospitalist while you figure it out.