[Release of copper ions after insertion of VCu200 IUDs].

In order to understand the life span of VCu200 IUDs in situ, the copper-ion concentrations in the cervical mucus were assayed after insertion of VCu200 IUDs for 5 years. Copper-ion concentrations were measured at random in 30 cases each of 1, 3, 6, and 12 monthth VCu 200 IUD users and 20 cases each of 24, 36, 48, and 60 month users. At the same time, 10 cases of the inserted-ring users were similarly studied for comparison. In addition, to obtain the normal copper-ion concentrations in the cervical mucus during the proliferative phase (8th-9th day), mid-period phase (10th-14th day) and the secretory phase (20th-23rd day) of a norma cycle, 16 cases of nonusers were selected as control. The measurements were assayed by a non-flame atomic absorption spectrophotometer. Samples of 0.2-0.4 gms of cervical mucus were collected in a glass tube from the IUD users on the 20th-23rd day of the menstrual period. There is a significant difference between VCu200 IUD users and nonusers (p 0.01) and ring users (p 0.01). The copper-ions released in VCu200 IUD users in different months were 2.61, 1.98, 1.96, 1.82, 1.22, 1.20, 1.15, 0.98 ug/g. w. w., respectively. The equation for regression line is y = -0.2764x+2.2340, which shows that the amount released decreased wtih increased time interval. However, the released amount of copper-ions at the end of 60 months was still higher in the users than in the nonusers (p 0.05). These results indicate that VCu200 IUDs can be left in situ at least 5 years without decreasing its biological activity in contraception.