Pie, making his first start in nine games, took a pitch and then fouled a ball off the plate. The ball came up and struck him squarely in the throat.
"They took him to get a CT scan on his throat," Orioles' manager Dave Trembley said. "He was hit squarely in the Adam's apple."
Orioles team trainer Richie Bancells rushed to Pie's side, who had walked a few feet toward the Baltimore dugout before taking a knee.
"He was a little light-headed," Trembley said. "It took the wind out of him. He said he was fine. We had the Oakland doctor look at him, and he recommended we take him out, so we did."
Pie struck out in the at-bat on a 2-2 delivery from A's rookie pitcher Trevor Cahill. Pie swung awkwardly at a pitch on the outside part of the plate.
Pie is hitting .200 on the season with a pair of home runs and four RBIs.
Rick Eymer is a contributor to MLB.com This story was not subject to the approval of Major League Baseball or its clubs.