Cech was withdrawn in the 18th minute of Tuesday's UEFA Champions League semi-final first leg after an aerial clash with Atletico Madrid striker Diego Costa.
Mark Schwarzer came on in Cech's place and performed admirably as Chelsea clung on to a clean sheet at the Vicente Calderon.
A statament from Madrid's Clinica Cemtro confirmed: "Petr Cech has been diagnosed of anterior shoulder dislocation at Clinica Cemtro after suffering a fall during the Champions League game against Atletico de Madrid.
"The player replaced the shoulder himself on the field of play.
"Once his shoulder was immobilized, Petr Cech has left the hospital for London, where his usual medical team will take care of his lesion."
Cech's absence throws 41-year-old Schwarzer into the limelight ahead of Sunday's crucial Premier League clash with Liverpool at Anfield with the return leg against Atleti to follow three days later.
"I'm always prepared and I'm getting used to this whole thing about sitting out and being ready to play at the last minute," Schwarzer told ITV Sport.
"It is always a tough thing to do, but I didn't have a chance to really think about it in this game. I just went out there and tried to do my job."
