The goalie was down for a short time after Penguins forward Kasperi Kapanen slid into him. Vanecek remained in the game, allowed a power-play goal to Evgeni Malkin at 6:26, and was replaced by Ilya Samsonov at 6:43.
"We'll evaluate it and see where he's at," Washington coach Peter Laviolette said.
Samsonov made 43 saves in the 4-3 overtime win.
"He played really well. He had a lot of work," Laviolette said. "They had a lot of offense and came at us in waves at times. Things we can do better next time we play them. That's not going to factor into tonight's game, so our goaltender needed to make some big saves. For him to come off the bench and play that way, he played a solid game. Gave us a chance."
Vanecek made 57 saves on 58 shots in his prior two starts, including 29 in a 5-0 win against the Dallas Stars on Friday. He was 10-6-5 with a 2.35 goals-against average and .916 save percentage in 23 games entering Tuesday.
Goalie Hunter Shepard was available to Washington from its taxi squad.
Washington hosts the Edmonton Oilers on Wednesday in its final game before the All-Star break (7 p.m. ET; TNT, SN, TVAS). Laviolette did not say who the starting goalie would be.
"I'll deal with that tomorrow," he said.
