Vessel occlusion method including the steps of positioning a coil anchor in a large diameter blood vessel, wherein the coil anchor includes a radially expandable sidewall, a proximal opening dimensioned to receive an embolic coil, a distal opening, and the coil anchor further comprising at least one coil retaining element configured to retain an embolic coil within the blood vessel. The vessel occlusion method further including the steps of expanding the coil anchor within the blood vessel and delivering at least one embolic coil into the blood vessel, wherein the retaining element prevents the at least one embolic coil from migrating downstream of the coil anchor.
