D'Arnaud reached into the path of baserunner A.J. Pierzynski after receiving a throw from left fielder Michael Cuddyer in the sixth inning at Turner Field. D'Arnaud's arm absorbed a jolt from Pierzynski's left leg that dislodged the baseball, and Pierzynski scored the go-ahead run.
After writhing in discomfort near the plate, d'Arnaud was escorted off the field by Mets staff. The team announced that X-rays were negative and that d'Arnaud is day-to-day.
D'Arnaud indicated it was "pretty painful" when he first absorbed the jolt, so he was relieved when the diagnosis was limited to the hyperextended elbow. He is dealing with inflammation in the elbow.
"A lot of negative thoughts were going through my head," d'Arnaud said. "I'm just very fortunate that it wasn't as serious as I was thinking. ... It just feels swollen. I'm sure a couple of ice treatments and I'll be good."
Manager Terry Collins said he feared a far more severe injury. Collins added that d'Arnaud likely could be used in an emergency situation Sunday, alleviating the need to call up a catcher from Triple-A Las Vegas.
"I thought he could have dislocated his shoulder," Collins said. "The hyperextended elbow, I know it hurts, but we've got tape. Those things you can take care of it. I know in an emergency, if we need him tomorrow, he'd be available. Right now we'll just wait to see how he is. But I thought the shoulder was gone, for sure."
The oft-injured d'Arnaud had returned 10 days ago after missing nearly two months with a fractured right pinkie. He suffered that injury when he was struck by a pitch from Miami Marlins reliever A.J. Ramos on April 19.