Umpire Brian O'Nora is recovering from an intestinal tear that forced him to make a sudden exit at a game last week.
Major League Baseball said Monday that there is no timetable yet for his return.
The 50-year-old O'Nora was feeling ill before Friday night's game in New York between Philadelphia and Mets. He was the plate umpire and quickly left the field during the bottom of the first inning, hurrying through the Mets' dugout. The game was delayed 9 minutes and resumed with three umpires.
O'Nora left Citi Field and went to a hospital to be examined.
O'Nora umpired in the World Series last year. He worked his first major league game in 1992 and has been on the big league staff since 1999.