Understanding the coupling between flow, hydrodynamic transport and dispersion of colloids of finite size in porous media is a long-standing challenge. This problem is relevant for a broad range of natural and engineered processes, including contaminant and colloidal transport, mixing of biochemical compounds, kinetics of reactions, and groundwater bioremediation, but also transport phenomena related to different systems like membranes or blood flow. While classical models for colloidal transport rely on macrodispersion theory and do not take into consideration the complex and heterogeneous structure of the porous host medium, recent studies take into consideration the detailed structure of the porous system and its impact on fluid velocity. However, the impact of confinement conditions, represented by the ratio of the radius of particles a and pore-throat size λ, has been overlooked. Here, we use numerical simulations of fluid particle dynamics in resolved porous media to demonstrate that particle confinement affects the fluid macroscopic velocity field which in turn affects the particle transport itself. Our results show that even under small confinement conditions (a/λ∼2 %), fluid and transported particles are dynamically rerouted toward more permeable paths. This leads to the emergence of ephemeral laminar vortices at pore-throat entrances and affects the variance and mean fluid velocity.