Systems and methods for performing and assessing neuromodulation therapy are disclosed herein. One method for assessing the efficacy of neuromodulation therapy includes positioning a neuromodulation catheter at a target site within a renal blood vessel of a human patient and delivering neuromodulation energy at the target site with the neuromodulation catheter. The method can further include obtaining a measurement related to a dimension of the renal blood vessel via a sensing element of the neuromodulation catheter. The measurement can be compared to a baseline measurement related to the dimension of the renal blood vessel to assess the efficacy of the neuromodulation therapy. In some embodiments, the baseline measurement is obtained via the sensing element of the neuromodulation catheter prior to delivering the neuromodulation energy.