Silverlily and Goldlily IUDs: do alloys create a new generation of intrauterine contraceptive devices?

I Batar

University of Debrecen, Department of Obstetrics and Gynecology, Debrecen, Hungary

Introduction The surface of copper in copper-containing devices oxidizes by time. Corrosion destroying the metal reduces the life span of the IUD because the copper becomes fragmented, and disappears from the plastic frame. The latest novelties, the alloy-containing devices try to solve this problem, and at the same time enhance the contraceptive effect by electrochemical mechanism.

Objective Two IUDs (Silverlily and Goldlily) having different alloy metals (Cu/Ag and Cu/Au, respectively) have been studied for effectiveness and safety in a prospective clinical trial.

Materials and methods The overall performance of 3,290 Silverlily and 4,055 Goldlily IUDs were analyzed in a human phase IV study. Life table (LT) calculation was used for statistical evaluation.

Results At the end of the first year of follow-up 1,954 and 2,253 women were at risk in the Silverlily and the Goldlily group, respectively. The cumulative woman-month of use was 27,762 in the Cu/Ag and 32,628 in the Cu/Au IUD user populations at 12 months. One-year relevant device-related termination rates/100 users for Silverlily and Goldlily were as follows: pregnancy 0.7 for both devices, expulsion 1.9 and 2.0, removal for bleeding/pain 6.1 and 5.3, respectively, and removal for other medical reasons 2.2 for both devices. There were not statistically significant differences between the groups in these relevant competing risks. However, terminations for all competing risks (including removals for planned pregnancy and other personal reasons as well) showed a significant difference (Chi-Square = 4.2673; Probability < 0.05) with rates of 13.7 for the copper-silver device, and 11.8 for the copper-gold IUD. It is explained by the fact that significantly more Silverlily (2.4) than Goldlily (1.3) were removed for planned pregnancy (Chi-Square = 7.5674, Probability < 0.01).

Conclusion Both devices showed good protection against unwanted pregnancy. Due to the low termination rates for other reasons, the continuation was high at the end of the first year of use: 86.3% in the Cu/Ag and 88.2% in the Cu/Au group. One may suggest that using different copper/noble metal alloys in intrauterine contraception leads to a new generation of IUDs.