As a first part of their series, authors discuss the clinicopathological problems of the tissue effects of copper-containing IUDs. They stress the possibilities of local injury caused by copper ions which play a role in enhancing the contraceptive effects.
PIP: This is a brief review of the effect of the endometrial milieu on the copper in a copper IUD. The local effect of the IUD on the endometrium depends on the material of the IUD, the amount of the surface in contact and the nature of that contact. Generally the foreign body effect of the IUD is due to a sterile inflammation. Copper was incorporated in IUDs as a result of the discovery that even traces of CU ion has a strong contraceptive effect, inhibiting transtubal sperm migration and preventing zygote formation. The copper on the IUD is oxidized to black copper oxide, which is then dissolved by the amino acids in endometrial fluid. Release of copper falls off exponentially, from about 1.6-4.7 mcmol/day initially to about 0.16-0.63 after 3-5 months. This decrease in dissolution of Cu ion is probably due to incrustation of organic material, then by calcium salts. Copper also corrodes electrochemically. Both process result in pitting and fragmentation of the copper wire, limiting its lifetime. Use of silver or alloys has been suggested to prolong the useful lifetime of the copper on the IUD.