In this work, in the process of plane-wave ultrasound probing from different angles the attainable spatial resolution was estimated on the basis of the previously developed theory of the Doppler response formation. In the theoretical calculations coherent compounding of the Doppler response signals was conducted over the period of changing the steering angles of probing. For this case an analytical expression for the ultrasound system sensitivity function over the field, which corresponds to the point spread function, is obtained. In the case of a rectangular weighting window for the response signals, the resolution is determined by the well-known sinc-function. The magnitude of the lateral resolution is inversely proportional to the range of the steering angles. It is shown that the theoretically estimated magnitude of the Doppler system lateral resolution, when using the technique of coherent plane-wave compounding, is in good agreement with the experimental data presented in literature.