[UPDATE: Pfeffer discloses to fans on his Facebook account that it was an emergency surgery and that he will be "out for a little bit."]

Dave Zeitlin, of MLSsoccer.com and CSNPhilly.com, reported live from the Philadelphia Union's Reserve League game against the DC United reserves that the Union's Zach Pfeffer underwent appendix surgery recently.

The 16-year-old Pfeffer was expected to start in the Reserve League game and his no show at the game caused some fans attending the match, or following the game through the Union's Twitter feed, to wonder where the midfielder was. On his Facebook account, Pfeffer said that he had returned home and was "feeling a little better...I'll be back on the pitch real soon!"

Zeitlin updated Union fans later on into the game, through Twitter, with the following:

For those that missed out, Zach Pfeffer had his appendix taken out today. Hackworth called it a setback for his U-17 World Cup hopes.

Pfeffer was part of the USMNT under-17 team that went to France during late April for the Mondial Minimes Tournament and was expected to push for a spot on the USMNT under-17 World Cup team in June.