Doumit was checked out by head trainer Brad Henderson immediately after showing those symptoms in the top of the fourth. Doumit was then taken to Allegheny General Hospital for additional tests.
Manager John Russell was unaware of those results and had little to report on the catcher's status during his postgame press conference.
"Hope for the best," he said. "I can't really comment because I don't have all the information. He felt a little dizzy, a little nauseated. We'll just have to see what he looks like [on Thursday]."
It appeared that Doumit's early exit was the direct result of his first-inning collision with Brewers second baseman Rickie Weeks, who came barreling down on Doumit as Delwyn Young's throw from right field short-hopped the Pittsburgh catcher and rolled to the backstop. The Brewers took a 1-0 lead on the play, and Doumit was left knocked over.
However, Russell suggested it might be more than a singular incident.
"It didn't look like it really banged him that hard," Russell said, also suggesting that the humidity, adrenaline and an incident from Monday might also have contributed to Doumit's dizziness.
Doumit was hit in the mask by a foul tip on Monday and had been held out of Tuesday's game for precautionary reasons. Though Doumit did not suffer a concussion in the incident, the Pirates felt no need to rush him back out onto the field given Doumit's concussion history.
The Pittsburgh catcher missed two games back in June with concussion-like symptoms.
Jenifer Langosch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.