The Cardinals placed Romero on the 15-day injured list Friday, retroactive to Tuesday, due to appendicitis.
Romero has been one of the most reliable members of St. Louis' bullpen as of late, allowing just two runs (one earned) while striking out nine batters and walking four across his last 10 innings, but he'll now have to wait until at least July 29 to make his first appearance of the second half. Scott Blewett will come up from Triple-A Memphis to fill the vacancy in the pen.