Bergesen was joined on his trip to the minors by fellow starter Chris Tillman, who was optioned Sunday following a 6-4 loss to the Oakland Athletics.
Bergesen fell to 1-6 with a 5.36 ERA after allowing three runs and nine hits during a loss Saturday at Oakland. His six losses are tied for second most in the majors.
The move was announced after midnight Saturday because the team had not been able to talk to Bergesen. He was born in Fairfield, Calif., a small city 30 minutes north of Oakland, and left quickly following the game to be with friends and family.
The Orioles called up left-hander Pedro Viola from Double-A Bowie to replace Bergesen.
Tillman started and pitched 4 1/3 innings against the A's on Friday but did not figure in the decision. The right-hander was 2-3 with a 4.69 ERA before being sent down. Baltimore did not announce a corresponding move.