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.