Coulombe was optioned to Triple-A Nashville on Monday.
The Athletics will make some wholesale changes to their bullpen in advance of Monday's series opener with the Twins, bringing up Andrew Triggs and Patrick Schuster from the minors to replace Coulombe and Fernando Rodriguez (shoulder), who is bound for the DL. Coulombe owned a 4.50 ERA, 1.28 WHIP and 15:5 K:BB ratio over 18 innings with the Athletics this season.