The nova-T vs the copper-T-200: Luukkainen T, Allonen H, Nielson N, et al: Five years' experience of intrauterine contraception with the Nova-T and the Copper-T-200. Am J Obstet Gynecol 147:885, 1983

Abstract

We studied the copper-releasing ability, weight and microscopic appearance of 2 copper-bearing intrauterine devices (IUDs), Copper-T Cu 200 (CuT) and Nova-T Cu 200 Ag (NovaT), after they had been in utero for up to 8 years. In addition, we studied whether IUDs removed from pregnant women showed different copper release.We found that IUD weight was a linear, negative function of duration of use, and that less than 20% of total copper would be released over a period of 8 years. The average copper-releasing ability was significantly higher for CuT than for NovaT (82.6 ± 6.4 vs. 42.7 ± 2.6 μg/day). The copper release was constant and thus unrelated to duration of use. Copper-releasing ability was similar in IUDs removed from pregnant and non-pregnant women. Fragmentation or minor defects only occurred in 3% of the IUDs and no correlation was found between deposits or corrosion and copper release rates.We conclude that CuT and NovaT both have constant copper release for at least 5–6 years and that the useful life-span probably can be prolonged to 6–8 years or more.