Dorrans, one of Albion's star performers this season, sustained a hip problem during Tuesday night's 1-1 draw at Ipswich and Roberto Di Matteo is anxiously waiting the results of a scan.
Bednar also suffered a bruised foot and both players will be assessed on Friday before a decision is made as to their availability.
Chris Brunt's superb individual display at Portman Road was dampened somewhat by a head wound that required a single stitch, but he is fine to feature against Kevin Blackwell's side.
Abdoulaye Meite has returned from the African Nations Cup after Ivory Coast were eliminated but whether he is included in Di Matteo's matchday 18 remains to be seen. January signing Marcus Haber is also eligible to make his debut after receiving international clearance.
James Morrison (heel) remains the only player definitely out.