Filter apparatuses and methods of using same

A filter device for implantation wholly within a gall bladder, comprising:

• a mesh or undulating wire formed into a self-expanding concave filtering blocking section tapering away from a center of the filter device and having a porosity selected to selectively block the passage of gall stones with a dimension greater than a specified minimum size;
• and,
• a resilient anchoring section which extends the length of the gall bladder from the blocking section located near a cystic duct opening of the gall bladder to a portion of the gall bladder substantially opposite the opening such that said length is sufficient to prevent movement of the blocking section away from said cystic duct opening of the gall bladder by a distal end of the anchoring section contacting said opposite portion and configured to be longer than and with a smaller radial dimension than the blocking section and terminating in a curved or looped end for a traumatic resting against said opposite portion,
• wherein the filter device is sized to wholly fit within a gall bladder and does not apply expansive radial force on a wall of the gall bladder for anchoring the device.