Earlier Wednesday, Strasburg traveled back to Washington to undergo further evaluation after he complained about tightness in his neck and shoulder during Tuesday night's win over the Braves in Atlanta. The 32-year-old pitcher was pulled after just 1 1/3 innings.
This is Strasburg's second trip to the injured list this season. He was shut down from April 15 until May 21 because of right shoulder inflammation.
That recent shoulder ailment played a part in Martinez's decision to remove the three-time All-Star pitcher so early in Tuesday's game.
"He was a bit frustrated," Nationals manager Dave Martinez told reporters before the club had received the latest update. "He came back, he felt good and then he had these issues with his neck going on with him [Tuesday]. I told him let's get him checked out and see where he's at."
Strasburg departed Tuesday's contest against the Braves after William Contreras' line drive hit his left arm near his glove in the second inning. Martinez and the Nationals' medical staff were concerned about Strasburg from the beginning of the game after he walked Ronald Acuna Jr. on four straight pitches.
The 2019 World Series MVP gave up one run on one hit and issued two walks while throwing just 30 pitches Tuesday. He has a 1-2 record and 4.57 ERA in five starts this year.
"I know he's frustrated because he feels he let the team down and let me down, but I don't want him to even think like that," Martinez said.
The Nationals recalled right-hander Kyle McGowin from Triple-A Rochester in a corresponding roster move. He has a 3.09 ERA over 10 relief appearances for Washington this season.