Ruiz took batting practice, but felt discomfort in his strained right oblique. He will be re-evaluated Tuesday.
Ruiz, who caught nine innings Sunday for the IronPigs, added a hit and a pair of walks.
He was placed on the disabled list April 11 and was scheduled to catch Tuesday for Double-A Reading. But that appearance and his exact return to the Phillies are unclear at this point.
Rookie Lou Marson got the start Monday night against the Nationals.
Andy Jasner is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.