Speaking right after Chicago's 10-2 loss, manager Joe Maddon said he hadn't watched the replay but was told Bryant was hit in the head/neck area.
"He's doing OK. He's still under evaluation,'' Maddon said. "We don't know exactly what we're doing with this whole thing yet. But we're trying to talk with the docs and find out exactly where we're at.''
Bryant was cleared to travel with the team to Houston for the start of its six-game road trip, which begins Monday. He walked through the Cubs' clubhouse after the loss to the Reds, but the media wasn't allowed to speak with him because he was still being evaluated.
Neither Bryant nor Heyward were in the Cubs' lineup for Monday's game against the Astros. The Cubs said Heyward has a sore hip.
With two outs and Nick Senzel on first, Heyward and Bryant converged on Eugenio Suarez's fly ball toward the gap in right-center. It looked as if Heyward and Bryant both called for it before running into each other, and the ball went off Heyward's glove.
Bryant, a natural third baseman who occasionally plays the outfield, stayed down as Senzel scored and Suarez hustled into third. Maddon and a trainer ran out to take a look, and the 2016 National League MVP walked off the field gingerly after a short conversation.
The loss of Bryant for any extended period would be a big blow for Chicago, which leads the NL Central by 1 ½ games over Milwaukee. Bryant is batting .345 (30 for 87) with nine homers and 21 RBIs in May.
The collision occurred during Bryant's eighth start in right this season. He also has made six starts in left, but Maddon said he didn't think the moving around was a factor in the play.
"I don't think so. I've seen some really stable outfielders, guys that are there all the time, do the same thing,'' he said. "They've been out there before together; [Heyward's] been in center, and K.B.'s been in right. It happened. It happened. It happens in our game. It's going to happen again. Hopefully not for a while.''
Asked if Bryant's relative inexperience in the outfield was a factor in the collision, Heyward responded Sunday: "You've got to ask him. You've got to ask K.B.
"We both were going hard to make a play and we ran into each other."
Asked if he was OK, Heyward said: "Any other questions?''
The Associated Press contributed to this report.