Frameless versus classical intrauterine device for contraception

The frameless intrauterine device (IUD) dispenses with the frame in the classical IUD and holds the device in the uterus by anchoring one end of a nylon thread in the fundal myometrium, to which copper sleeves are attached.

This review examines the hypothesis that the frameless IUD Gynefix reduces risk of expulsion and pregnancy, and the problems of bleeding and pain necessitating early removal.

We searched the Cochrane Controlled Trial Register (Cochrane Library Issue 2, 2004), MEDLINE, and Popline from 1980 to March 2004, and reference list of articles.

We selected for the review randomised trials that compared the frameless device to a classical framed device for contraception.

Both authors extracted data independently. We contacted study author for additional data. We calculated rate ratios and rate differences for cumulative rates for each outcome at yearly intervals. We used the inverse variance-based method to combine trials, and tested the results for heterogeneity.

Four trials were included in the review involving 5,939 women randomised to either a frameless device or TCu380, with data up to eight years for the largest, and with a total experience of 23,180 years. Apart from one small trial, nulliparous women were excluded from the trials. The two earlier trials used a prototype introducer and there was a higher expulsion rate at one year (relative risk 2.48, 95% confidence intervals 1.89 to 3.26). However, between two and six years in the large WHO trial the risk of pregnancy was lower with the frameless device (relative risk 0.53, 95% confidence intervals 0.32 to 0.91). In a recent trial using GyneFix with a new introducer early expulsions and pregnancies were not statistically different from the control device. Removals rates for excessive bleeding and/or pain were no different between the devices (relative risks 0.92, 95% confidence intervals 0.74 to 1.14, at one year and 1.13, 0.93 to 1.37, at six years). There was a tendency towards fewer removals for pain in early years but no difference at six years (relative risk 1.13, 95% confidence intervals 0.93 to 1.37).

There is insufficient data to show that problems of early expulsions have been overcome with the modified introducer used in GyneFix. Apart from that, the frameless device performs similarly to TCu380, and appears to have a lower pregnancy rate in later years, although the absolute difference is small.