Spokeswoman Jean Becker said Sunday that Bush has not been diagnosed with anything and doctors aren't looking for anything specific.
Former President George H.W. Bush drove his wife to Methodist Hospital on Saturday morning. Becker said earlier that the former first lady hadn't been feeling well for about a week, and doctors suggested she "undergo a battery of tests."
Mrs. Bush underwent heart surgery in March 2009, for a severe narrowing of the main heart valve. She also was hospitalized in November 2008, when she underwent surgery perforated ulcer.
