Coulombe was optioned to Triple-A Nashville on Wednesday, Jane Lee of MLB.com reports.
Coulombe had his contract selected by the A's on Tuesday, and he'll now head back to Triple-A after throwing two innings in Tuesday's 13-5 loss to Boston. Coulombe allowed three hits and three earned runs in his only major league appearance of the season. In a corresponding move, the A's recalled Eric Surkamp from Nashville.