Marcos Rojo is the only senior central defender available for Saturday's match, the United manager revealed at his pre-match press conference on Thursday.
Jonny Evans suffered a bruised ankle in the 5-3 defeat to Leicester and Tyler Blackett is suspended following his dismissal at the King Power stadium.
Chris Smalling was injured in training on Wednesday and will not feature against the Hammers while Phil Jones remains sidelined with a hamstring problem, the United boss said.
Van Gaal said: "All the three right-sided centre-halves are out.
"I don't know how long they will be out for.
"Evans is a very difficult one
His bone is bruised a lot and we have to wait and see, to evaluate it.
"Smalling yesterday ran out of the training session because he had stiff legs.
"We have to see what that means
But I don't take risks with players."
Source : PA
Source: PA