The Senegalese attacker suffered damage to his shoulder and collarbone when he landed poorly after Wesley Hoedt struck him in the back whilst competing for an aerial ball in the first half, and needed to be administered oxygen in the dressing room following his departure from the pitch.
He has since undergone extensive tests. But there was a need for further checking due to the fact that swelling can sometimes render results inconclusive.
Diouf will miss Stoke's matches against Manchester City and Everton, but there's also a fear over him being unable to return to action this season.
Team medics are hoping that two weeks of resting will be enough for the player to heal, but if not, he could require corrective surgery that will rule him out of the nine fixtures Stoke have remaining.
The striker's work rate is understood to have won new boss Paul Lambert over very quickly. And he has started five matches out of the six the manager has been in charge of since his taking over from Mark Hughes.
But Lambert will only have Peter Crouch and Jese to call upon for the next two matches at least, leaving him with a big gap to plug.