Degradation of the coer‐releasing intrauterine contraceptive device and its significance

Abstract

summary Measurements were made of the coer remaining on used Gravigard intrauterine contraceptive devices (lUCDs) that had been in utero for up to 40 months. The topography and composition of the surface deposits were analysed by scanning electron microscopy and energy‐dispersive X‐ray analysis. The rate of coer loss decreased exponentially from 0–42 μmol d−1 (26–7 μg d−1) upon insertion to 0‐056 μimol d−1 (3–6 μg d−1) after 26 months of use; between 27 and 40 months of use a linear release of 0–32 μimol d−1 (20–3 μg d−1) was observed. There was no correlation between this changing rate of coer loss and the pregnancy rate with the device in situ. The changes in the rate of coer loss were probably due to the growth of a surface corrosion product which, due to internal stresses, fractured after about 2 years and exposed fresh coer; this results in a progressive increase in breakage of the coer wire after 3 years. It is recommended that a coer IUCD of this type be replaced after 3 years.

An analysis of the corrosion process of the nova-T IUD

“…This study has shown that there is no significant difference in the rate at which copper is lost from the Nova-T, which has a silver core, compared with the Gravigard [6], which has the same surface area but is a pure copper coil. It can be seen that there is an apparent tendency for the Nova-T to lose marginally less copper than the Gravigard during the first two years of use; however, this finding would only be reliable if there was a single initial copper content, common throughout the Nova-T devices studied here.…”

“…Examination of cross-sections along the copper coil confirmed the uneven corrosion of the copper, being reduced where the copper contacts the polyethylene former [6,15]. As a consequence, copper is initially dissolved preferentially from the outward-facing parts of the coils.…”

“…To retain consistency with our previous analysis conducted on the rate of copper loss from used Gravigard IUDs [6], a transition regression analysis was attempted on these data. No evidence of a transition point (i.e.…”

“…A detailed analysis of the rate of copper loss from the Gravigard IUD [6] revealed an unexpected pattern of copper loss during use. It was shown that the rate of copper loss decreased up to 26 months of use when a change in the rate of copper loss occurred.…”

Corrosion characteristics of copper‐based IUDs

“…This limits the effectiveness of the IUD by lowering service life of the device and by causing adverse side effects for IUD users (uterine bleeding, uterine perforation risks and accidental pregnancy) (Chantler et al, 1984;Yuan et al, 1986). Corrosion products had a tendency to form passive layers (i.e.…”