A powered reamer comprising a stationary assembly having a flow bore therethrough. A rotating assembly is disposed about the stationary assembly and one or more cutting structures are coupled to an outer surface of the rotating assembly. A flow restriction is disposed within the flow bore so as to divert a portion of fluid flowing through the flow bore through an outlet from the flow bore into an annulus between the stationary assembly and the rotating assembly. A power section is formed in the annulus between the stationary assembly and the rotating assembly. The power section operates to eccentrically rotate the rotating assembly about the stationary assembly in response to fluid flowing through the annulus between the stationary assembly and the rotating assembly.