Braves manager Brian Snitker took Swanson out as a precaution. He said Swanson's wrist "is a concern" because it was bad enough that he had to exit the game.
Swanson underwent tests Tuesday night. He missed 13 games earlier in the season with left wrist inflammation.
Swanson left the game after flying out to center in the second and was replaced by Charlie Culberson in the field for the third inning.
Swanson, the first overall pick in the 2015 draft, is having a bounce-back season after a disappointing 2017. He is hitting .238 with 14 homers and 59 RBIs.