Bernd Leno started in goal against Chelsea on Sunday, but Ramsdale is likely to come in for the trip to The Hawthorns.
Martin Odegaard could also start after getting visa clearance following his £30m move from Real Madrid last week.
Arsenal will still be without Ben White (Covid-19), Eddie Nketiah (ankle) and Thomas Partey (ankle), but Gabriel could make the squad as he recovers from a knee issue.
Alexandre Lacazette could also make the bench after recovering from Covid-19, while Kieran Tierney and Gabriel Martinelli have shrugged off cramp issues from the weekend.
Arsenal likely XI (4-2-3-1): Ramsdale; Chambers, Holding, Mari, Tavares; Elneny, Xhaka; Saka, Odegaard, Smith Rowe; Aubameyang
Wednesday 8.00pm BST, Sky Sports
Arsenal squad from: Leno, Ramsdale, Runarsson, Okonkwo; Bellerin, Cedric, Chambers, Gabriel, Holding, Kolasinac, Mari, Tavares, Tierney; Elneny, Lokonga, Maitland-Niles, Odegaard, Saka, Smith Rowe, Torreira, Xhaka; Aubameyang, Balogun, Lacazette, Martinelli, Nelson, Pepe and Willian
Doubts: Bellerin (thigh), Gabriel (knee), Willian (Covid-19)
Out: Nketiah (ankle), Partey (ankle), White (Covid-19)