Manager Gabe Kapler said Dominguez showed symptoms of a mild elbow sprain and will undergo an MRI on Thursday, Bob Brookover of The Philadephia Inquirer reports.
Dominguez was apparently having some issues with his right elbow and was removed from Wednesday's game after recording one out and allowing two runners to reach base. It's difficult to imagine the 24-year-old being cleared to pitch Friday's series opener against the Reds, but more information should be available after the MRI.