"There's no fractures," said manager John Farrell. "It's still going to take a few days here for him to get back to full mobility and be able to rotate as he normally does swinging the bat."
The Red Sox have an off-day on Thursday and could hold Pedroia out until Friday at home against the Angels, but Farrell didn't rule him out entirely for the series in Kansas City, which ends with a Wednesday matinee.
"I don't know about that. He's going to need at least a couple of days," Farrell said. "When we get to Wednesday's game, we'll kind of see where we are and with the off-day Thursday, all of that will be factored in."
Josh Rutledge started at second base in Pedroia's absence on Monday.
Pedroia was hit in the seventh inning and was able to run the bases before exiting prior to the bottom of the ninth inning.
"I mean, I was fine on the bases," said Pedroia. "I tried to steal third, I was fine. And then the next inning, I was kind of spitting up a little bit of blood, so that kind of freaked out and they made me go get tested to make sure everything was OK. I could have bit my lip. [My back] was pretty swollen and big and gross."
Pedroia's body has taken a beating this season. Manny Machado slid into Pedroia's surgically-repaired left knee on April 21, forcing him out of the lineup for a few days. In the first inning of a Memorial Day matinee at Chicago, Pedroia collided into White Sox first baseman Jose Abreu and wound up on the 10-day disabled list with a left wrist sprain.
The Red Sox are relieved this latest injury wasn't worse.
"I think after we saw Pedey last night in the ninth inning, the way it was reacting and the quick swelling, we were fearing the potential of a fracture in there," said Farrell. "Thankfully there's not and we'll get him back there when he's first available."
The temporary loss of Pedroia left the Red Sox without a backup infielder for Monday's game.
"[President of baseball operations] Dave [Dombrowski] and I have talked daily about just the status of our roster and the need to carry the extra pitcher for the short term, and we'll have a chance to assess where we are after tonight's game," said Farrell.
• Red Sox left-hander Eduardo Rodriguez is starting to turn a corner in his comeback from a right knee subluxation and could face hitters in a simulated game type of setting by the end of the week. After that, the next step would be for Rodriguez to go on a Minor League rehab assignment. Given that Brian Johnson is also on the disabled list with a left shoulder impingement, the return of Rodriguez is vital for Boston.
"He went through some further agility work here today. He went through some after his bullpen [session] yesterday," said Farrell.
Ian Browne has covered the Red Sox for MLB.com since 2002. Follow him on Twitter @IanMBrowne and Facebook. This story was not subject to the approval of Major League Baseball or its clubs.