The Mets placed the 27-year-old right-hander on the 10-day disabled list, although it’s possible he won’t return at all this season.
Familia had the procedure performed in St. Louis by Dr. Robert Thompson, who also treated starter Matt Harvey last year when he had thoracic outlet syndrome.
Alderson said the blood clot was in the armpit area on Familia’s right side. The pitcher first mentioned he was feeling symptoms Wednesday. Later that day, he blew a save against the Giants, allowing four runs (three earned) on two hits and two walks while retiring just one batter.
“We do believe that this is something that will keep him out several months,” Alderson said. “It’s possible that he’ll be back by the end of the year. It’s possible he won’t. We just don’t know at this point.”
In 11 appearances this season, Famila is 1-1 with a 3.86 ERA and three saves. He was suspended for the first 15 games for violating Major League Baseball’s domestic violence policy.
Last year, Familia led the majors with 51 saves.
The Mets filled Famila’s spot on the roster by activating first baseman Lucas Duda from the DL. Duda had been out since April 20 with a hyperextended left elbow.
Familia joins a long Mets disabled list that also includes starting pitchers Noah Syndergaard, Steven Matz and Seth Lugo, outfielders Yoenis Cespedes and Brandon Nimmo, third baseman David Wright and catcher Travis d’Arnaud.
Addison Reed, who earned four saves during Familia’s suspension,will fill in again as the Mets’ closer while Familia is out.