HOUSTON — Former first lady Barbara Bush remained hospitalized in Houston on Sunday, where she was undergoing what a family spokeswoman described as routine tests.

Spokeswoman Jean Becker said that Bush had not been diagnosed with anything and doctors were not 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.

Doctors at the time said the condition was common among people her age.

She also was hospitalized in November 2008, when she underwent surgery for a perforated ulcer.

A hospital spokeswoman declined comment, saying information was only being released through the family.