Renormalized Solutions to Stochastic Continuity Equations with Rough Coefficients

We consider the stochastic continuity equation associated to an It^{o} diffusion with irregular drift and diffusion coefficients. We give regularity conditions under which weak solutions are renormalized in the sense of DiPerna/Lions, and prove well-posedness in $L^p$. As an application, we give a new proof of renormalizability (hence uniqueness) of weak solutions to the stochastic continuity equation when the diffusion matrix is constant and the drift only belongs to $L_t^q{L}^p$, where $\frac{2}{q}+\frac{n}{p}<1$, without resorting to the regularity of the stochastic flow or a duality method.