A vascular occlusion device for use with a hydraulic deployment catheter is provided. The vascular occlusion device includes a headpiece that has a deformable interference element which changes from an initial configuration to a deformed configuration upon an increase of hydraulic pressure within the deployment catheter. When the interference element is in the initial configuration, the headpiece is secured to the deployment catheter, and when the interference element is in the deformed configuration, the headpiece can be removed from the deployment catheter for deployment of the occlusion device.