Pellegrini's men eased to a 2-0 win over West Ham at the Etihad Stadium on Sunday thanks to a bizarre James Collins own goal and Sergio Aguero's strike.
But their victory was marred by the blow to Silva, who was caught in the side of the head by an elbow from West Ham midfielder Cheikhou Kouyate in the 67th minute and taken off on a stretcher following lengthy treatment.
Pellegrini told BBC Sport: "At this moment he [Silva] is in hospital and they are checking if he has a broken bone in his cheek.
"The referee was very near. He decides what happens and gave a yellow card. I hope that it was an accidental collision."
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