Tottenham goalkeeper Hugo Lloris was taken to hospital after suffering a serious arm injury early in the 3-0 defeat at Brighton on Saturday.
The France international fell awkwardly after failing to hold a Pascal Gross cross in the third minute, with Neal Maupay nodding in the loose ball.
Lloris received oxygen before he was taken off on a stretcher and replaced by Paulo Gazzaniga.
"It's not good news from the hospital," Pochettino told BBC Sport.
"But to have a better idea we will explain properly through the club, where they will explain what is going on with him."
Tottenham went on to lose the game at the Amex Stadium 3-0.
Lloris, who has made eight appearances for Tottenham this season, will now be a doubt for France's upcoming Euro 2020 qualifiers against Iceland and Turkey.
Defeat was a huge blow for Spurs as they looked to recover from a 7-2 defeat at home to Bayern Munich in the Champions League on Tuesday.