Model-independent conditions ensuring consistency of the single-particle mass operator and the amplitude of nucleon-nucleon scattering in nuclear matter are obtained in a form that is appropriate for the problem of describing excited states of even-even nuclei beyond the random-phase approximation. In a sense, this form of the consistency conditions makes it possible to solve the problem of separating the 1^- ghost state in models that take into account the contribution of complex configurations to the structure of ground and excited nuclear states.