The right-handers were being examined Monday by Dr. James Andrews in Gulf Breeze, Fla. The team says it doesn't expect to get any news on their conditions before Tuesday.
"They know they're injured. It's just a matter of finding out how badly they're injured,'' Braves president John Schuerholz said. "We're not counting on either of them. I mean, we hope that's not right, but that's the way we're planning.''
Both left their most recent spring training starts. Medlen has ligament damage and already said he expects to undergo the second Tommy John surgery of his career. Beachy didn't think his condition was serious at first, but he's had multiple setbacks since ligament replacement surgery in 2012 and seemed resigned to undergoing a second Tommy John procedure himself.
"It wasn't what I would have liked it to have been," Beachy said Friday of his initial test results, according to MLB.com. "I was pretty confident when I left the game on Monday. That was based on what I was told. I was being honest. Now it looks like it might be something else. It's frustrating, very frustrating."
Medlen and Beachy were expected to be stalwarts of the Braves' rotation. After they went down, the team hastily signed free agent Ervin Santana to a $14.1 million, one-year contract.
Both Santana and left-handed starter Mike Minor threw live batting practice Monday and the Braves said on their Twitter account that both pitchers are "progressing as planned."
Minor, who reported to camp with shoulder soreness, said he "felt good" Monday after facing batters for the first time this spring.
The Associated Press contributed to this report.