Ovarian vein coiling (or ovarian vein embolisation) is a technique for blocking the ovarian vein if it becomes incompetent.  Incompetence occurs when the valves in the ovarian vein do not work and the flow is down into the pelvis (rather than out of the pelvis). It is one of the causes of pelvic congestion syndrome and may also cause varicose veins in the legs.  To treat this, one can block the vein completely to prevent the flow into the pelvis.  To block the incompetent vein, one can put special coils into the vein.  This blocks off the incompetent ovarian vein and causes it to become a thread of scar tissue.  the coils are made of a special metal core with fine fibres attached which irritate the vein wall so that it collapses down and blocks off.  The blood then drains through veins where the valves are working and the return out of the pelvis is improved.