An analysis of the corrosion process of the Nova-T IUD.

OBJECTIVE

To measure the copper from Nova-T IUDs that have been used for up to 9 years. To examine the composition and extent of surface deposits on these used IUDs.

DESIGN

Nova-T IUDs were randomly collected at normal replacement or removal. The copper, silver and calcium content was quantified by X-ray fluorescence; surface topography and analysis was by scanning electron microscopy and X-ray dispersive analysis.

RESULTS

Copper loss slowly increased at an exponential rate over the study period but the copper was stabilized by the silver core and did not show increased fragmentation with extended use. No corrosion of the silver core was detected. Calcium- and sulfur-containing surface deposits built up on the copper but did not modify the rate of copper release.

CONCLUSIONS

The mean rate of copper loss was 0.25 mumol/day during the first 40 months of use, which is not significantly different from that of similar IUDs without a silver core. The silver core of the copper coil on the Nova-T IUD prevented its fragmentation. Surface deposits containing calcium and sulfur that built up on the IUD did not affect the rate of copper loss.