Worley was sidelined by right elbow inflammation and was scheduled for an MRI. Manager Charlie Manuel said the team should know more when it gets the results of Wednesday's exam.
"It seems like all of the sudden we lose guys for starts," Manuel said. "That doesn't help, neither. We need our guys to make all the starts if possible. That's kind of how it goes and you've got to deal with it."
Worley is 3-2 with a 3.07 ERA in seven starts this season. He struck out nine over six innings in a 7-3 victory over San Diego on Friday.
Worley was originally scheduled to start Wednesday night at Chicago but was replaced by Kyle Kendrick. His DL stint is retroactive to May 12.
Philadelphia, which has won five consecutive NL East titles, is off to a slow start due in part to several key injuries. Sluggers Ryan Howard and Chase Utley have yet to play this season, Jim Thome is out with back problems and left-hander Cliff Lee was just activated from the DL on Wednesday after he was sidelined with a left oblique strain.
Manuel said he knew Worley was getting treatment after his outings, but he didn't know the extent of the inflammation until Tuesday.
Reliever Joe Savery was recalled from Triple-A Lehigh Valley to take Worley's spot on the roster.
The promotion puts four left-handers in the Phillies' bullpen.
"If we want to put some lefties on left-handed hitters, I think we're stocked," Manuel said with a grin.
Philadelphia also made a minor trade on Wednesday, sending outfielder Rich Thompson to Tampa Bay for minor league outfielder Kyle Hudson. Thompson hit .307 in 29 games for Lehigh Valley but hasn't appeared in the majors since 2004, when he was with the Kansas City Royals for six games.
Jay Cohen can be reached at http://www.twitter.com/jcohenap