Hawkins has been pitching through back pain the past few weeks, and Astros general manager Ed Wade said the procedure was performed to double-check Hawkins' upper back.
The right-hander is 1-4 with a 2.36 ERA and 10 saves in 40 games this year. He was expected to join the team in time for Monday night's game at Wrigley Field.
Brian McTaggart is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.