Wacha was hit by a foul ball off the bat of teammate Matt Adams.
#STLCards press box announcement: Wacha was struck on right elbow by that foul ball; diagnosed with a contusion.
— Jenifer Langosch (@LangoschMLB) May 22, 2014
Wacha was at 88 pitches at the time of the foul ball. It looks like he had avoided any serious injury but his next start could be pushed back regardless.
On the season Wacha owns a 2.54 ERA and a 1.14 WHIP. In six innings of work against Arizona on Wednesday he allowed two hit and three walks while striking out four.