The effect of autoionizing resonances on ionization has been studied since the historic work of Fano. In the autoionization problem, it is not possible to distinguish electrons, that have been directly ejected from the atom, from those that were first excited to an autoionizing resonance level because of the extremely short lifetime. As a result, these two processes will interfere. Furthermore if the energy difference between the resonances is not larger than the width of the resonances, the resonances will also interfere with each other. In this paper, we examine electron-impact ionization $(e,2e)$ for cadmium in the energy range where the autoionizing resonances overlap and interfere. First-order distorted-wave results will be compared with recent measurements and previous calculations.