There is no timetable for Bradley's return to the Seattle lineup, though that could change following the results of the operation scheduled to be performed by Reds team physician Dr. Timothy Kremchek.
Bradley, currently on the 15-day disabled list with right knee tendinitis, has not played since July 26.
"We want to find out what's going on," Mariners interim manager Daren Brown said. "He's obviously had some pain and discomfort. Hopefully, they can clean it up a little bit and we'll go from there. We'll wait and see. We'll let the doctors do their thing and they'll give us an idea."
"I have nothing to say," he said.
Acquired from the Cubs in December, the 32-year-old Bradley is batting .205 with eight home runs and 29 RBIs in 73 games this season.
"It's always tough when you're not on the field," Brown said. "I don't think anybody looks forward to surgery, so I would say it's disappointing. But there's also a little bit of relief, because we'll hopefully find out what's causing the discomfort."