MILWAUKEE -- The latest blow in what has been a long line of injuries to key members of the roster could leave the Mets without their closer for the remainder of the season.
Jeurys Familia underwent surgery Friday to address a blood clot in his right armpit area.
The procedure, performed by Dr. Robert Thompson in St. Louis, could be season-ending, according to general manager Sandy Alderson.
"I don't have the results of the surgery, but we believe this is something that's going to keep him out several months," Alderson said. "It is possible he'll be back by the end of the year, it's possible he won't. We just don't know at this point."
Familia first reported feeling a tingling sensation in his right ring finger to a member of the Mets' training staff prior to Wednesday's 6-5 loss to San Francisco at Citi Field.
He was evaluated at that point and was cleared to pitch in the game, in which he blew the save and took the loss, recording just one out and allowing four runs (three earned).
Due to mild vascular symptoms, Familia was referred to the Hospital of Special Surgery in New York for a magnetic resonance angiography. The MRA, performed Thursday morning, revealed the blood clot.

Familia was then referred to Thompson, the same surgeon who performed Matt Harvey's operation for thoracic outlet syndrome in July.

"He had been coming in for just routine maintenance, if you will," Alderson said. "He came in Wednesday for that routine maintenance and mentioned this in passing. He was cleared to pitch [Wednesday]. Really it was a minor vascular symptom they wanted to follow up on as a precaution, which is what they did the following day. That right ring finger, Jeurys said he doesn't even use that finger when he pitches, so he was cleared to pitch."
Alderson said the Mets will first look to internal options to fill the void before exploring external candidates on the trade market.
Familia recorded 51 saves in 2016 and had converted all three of his 2017 chances, with just one earned run allowed, prior to Wednesday.
"This is a big one," Mets manager Terry Collins said. "This guy is arguably one of the best closers in the game. We lost one of the best starters in the game for a while, and now we've lost one of the best closers in the game for a while."

Addison Reed will serve as New York's closer for the immediate future. The 28-year-old recorded four saves while Familia was suspended for the first 15 games of the season for violating the league's Joint Domestic Violence, Sexual Assault and Child Abuse Policy.
From there, Collins said he plans to mix and match relievers such as Jerry Blevins, Hansel Robles and Noel Salas to get to Reed.
Familia joins seven other Mets on the disabled list, including several expected key contributors in Yoenis Cespedes, Travis d'Arnaud, Seth Lugo, Steven Matz, Noah Syndergaard and David Wright.
Out since April 20 due to a hyperextended left elbow, first baseman Lucas Duda was activated from the disabled list Friday.
"These are mostly veterans in that clubhouse, and they get the ups and downs of the game," Collins said. "They don't get too frustrated. I think that's the only way to go about it.
"Now they are challenged with another situation that they're going to have to deal with. I don't think there's a better group put together that can deal with it than these guys, because they proved they can do it last year."