The value of transvaginal ultrasound to monitor the position of an intrauterine device after insertion. A technology assessment study

BACKGROUND: The intrauterine device (IUD) is an effective contraceptive method. The contraceptive power as well as the side-effects of IUD are thought to relate to the position of the IUD in the uterine cavity. We assessed the accuracy of clinical evaluation of IUD position. METHODS: A prospective comparative study was performed. The clinical evaluation was compared with the TVU measurement of IUD position both immediately after insertion and 6 weeks after insertion. The primary outcome measures were the positive and negative predictive values (PPV and NPV) of the clinical evaluation of IUD position. RESULTS: 195 women were included consecutively, 181 women (92.8%) were available for follow-up. The PPV and NPV of clinical evaluation of IUD position immediately after insertion were respectively 0.60 (95% CI: 0.39-0.81) and 0.98 (95% CI: 0.96-1.0). The prevalence of an abnormally positioned IUD was 7.7% (95% CI: 3.9-11.4). The PPV and NPV of the clinical evaluation at follow-up were respectively 0.54 (95% CI: 0.26-0.81) and 1.0 (95% CI: 0.98-1.0). The prevalence of abnormal position was 4.0% (95% CI: 1.7-7.1). CONCLUSION: Clinical evaluation is an excellent test for the evaluation of the position of an IUD and routine TVU is not indicated for this purpose.