Corrosion and weight loss from copper wire in the Fincoid IUD in utero.

A total of 190 Fincoid IUDs were removed after varying periods of use in utero. Of 84 wires removed after 4 years of use, the 1st 12 wires were SEM photographed. In 1 of these wires, which was fragmented, a SEM photograph revealed deep corrosion pits. In the 11 unbroken wires, SEM photographs disclosed no clear pitting corrosion. Among 84 copper wires removed after 4 years of use, there were 4 fragmented ones. The risk of fragmentation after 4 years was thus 4.8%. Among the 106 copper wires removed for different reasons before the lapse of 4 years, there was not a single fragmented one. Annually, the mean daily release of copper ranged from 40.2 mcg to 43.3 mcg without any markedly higher initial release, 80% of the original weight still existing in the copper wires after 4 years in utero. The low incidence of pitting corrosion and fragmentation is most probably attributable to the higher positioning of the copper wire on the IUD. It is concluded that the effective life of the Fincoid IUD is more than 4 years.