RESUMEN
PURPOSE: To compare by transvaginal ultrasound the position of the intrauterine device (IUD) inside the uterine cavity, depending on the time of insertion, postpartum and post-abortion, and during the menstrual cycle. METHODS: Epidemiologic, observational and cross-sectional study carried out between February and July, 2013. A total of 290 women were included, 205 of them with insertion during the menstrual cycle and 85 during the postpartum and post-abortion periods. The independent variables were: age, parity, time of use, insertion time, number of returns to family planning, satisfaction with the method, wish to continue using the device, symptoms and complications. The dependent variable was the adequate position of the IUD inside the uterine cavity. The χ² test with Pearson's correction and the Fisher exact test were used for statistical analysis, with the level of significance set at 5%. RESULTS: The average age was 29.4 years and the average time of IUD use was 2.7 years; 39.3% of the women had symptoms associated with the method, the most frequent being menorrhagia (44.7%). The degree of satisfaction was 85% and 61.4% of the women returned two or more times for consultation about family planning. Age, parity and the position of the uterus in the pelvic cavity was not associated with a poor position of the IUD inside the uterine cavity (p>0.05). Insertion during the menstrual cycle was significantly more associated with a correct position of the IUD than postpartum and post-abortion insertion (p<0.028). CONCLUSION: Postpartum and post-abortion insertion showed worse results regarding the adequacy of IUD position, a fact that was not observed regarding age, parity or position of the uterus in the pelvic cavity.