The France international is to have surgery on Monday on an ankle injury sustained in training this week, leaving the Toffees boss with only the inexperienced Niels Nkounkou as cover.
"It is a big loss because he is one of the best left-backs in Europe at the moment but we have to manage this," said Ancelotti of Digne's injury ahead of the visit of Leeds on Saturday.
"I think we will be able to adapt to the loss of Lucas Digne for two or three months.
"Three centre-backs can be an option still. We can use Iwobi on the left without problem as a wing-back so we will see."