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Dr. Jim Shelton's Pearls "Pearl" for the week of July 31, 2003

Contraceptive Pearl - How long for EC?

Sometimes the IUDs we get seem to have lost some of their shine. I also remember a few years back that with quite a few of them, the copper looked pretty tarnished. Does such tarnishing affect the effectiveness of the IUDs?

No. Air normally passing into the IUD package can cause oxidation to occur resulting in tarnish. The effectiveness of copper IUDs depends on release of copper ions, which are actually produced by a similar oxidative process anyway. A study carried some years ago found that when tarnished IUDs are placed in media resembling uterine fluids, the tarnish rapidly dissolved and copper release rates for the tarnished and untarnished IUDs were the same.

References:

1. Tsong YY, Nash H. Effect of tarnish on copper release. Contraception 1991;44:385-392.

(A special thanks to Tony Hudgins of John Snow who prompted this Pearl)

The "Pearls" offer answers to commonly asked questions about family planning. These "Pearls" are prepared by Dr. James D. Shelton, Senior Medical Scientist, Office of Population, United States Agency for International Development (USAID)

Disclaimer: The information provided on this web site is not official U.S. Government information and does not represent the views or positions of the U.S. Agency for International Development, the U.S. Government or The Johns Hopkins University.