A 2D phase field model has been developed to describe the shape of a pore formed within interdendritic liquid channels. The influence of the solid, which can force the pore to adopt a non-spherical shape, is taken into account through the geometry of the domain and appropriate boundary conditions. The results show that the presence of solid call substantially influence the volume and pressure of the pore. A pore constrained to grow in narrow liquid channels exhibits a substantially higher mean curvature, a larger pressure and a smaller volume as compared witha pore grown under unconstrained conditions. The effect of pore pinching by the solid network was also evidenced by 3D characterization of a pore by X-ray tomography. These measurements showed high interface curvatures corresponding to an overpressure of more than 400 kPa.