Uterine volume, menstrual patterns, and contraceptive outcomes in users of the levonorgestrel-releasing intrauterine system: A cohort study with a five-year follow-up

Abstract

Objective: The aim of our study was to evaluate the effects of the LNG-IUS on uterine volume, bleeding patterns, and LNG-IUS-related outcomes among women using the device to treat abnormal uterine bleeding caused by fibroids, adenomyosis, HMB (without structural cause), or contraception.

Study design: This was a 5-year cohort study with LNG-IUS users. We selected 147 women, who were allocated to four groups: a) control (contraception indication); b) fibroids; c) adenomyosis; d) HMB. The visits for clinical and ultrasound evaluations were made at baseline and at 3, 6, 12, 24, 36, 48, and 60 months postinsertion. All data are expressed as mean and standard deviation (SD) or absolute and relative (%) frequency. Differences among groups were established by using the χ2 (chi-square) test and Fisher's exact tests for categorical outcomes, as well as the Mann-Whitney and the Kruskal-Wallis tests and Friedman's ANOVA for continuous variables. We used the 5% significance level as an indication of statistical significance. Logistic regression analyses were performed to study the association between predictors and outcomes. Results are expressed as odds ratios (ORs) with a 95% confidence interval (CI 95%).

Results: Although all groups had real rates of bleeding patterns, troublesome bleeding appeared to be more frequent in the fibroid group (∼15%). Also, along the 60 months of follow-up, uterine volume slightly decreased in the groups of HMB, adenomyosis, and fibroids, but not in the contraception group. However, the isolated volume of fibroids remained unchanged. In this cohort, we observed high continuation rates among LNG-IUS users. The uterine volume ≥200 cm³ was the main predictor of hysterectomy or IUS expulsion in the adenomyosis and fibroid groups.

Conclusion: The LNG-IUS may control uterine menstrual bleeding as well as uterine volume in adenomyosis, fibroids, and HMB. An initial uterine volume smaller than 200 cm³ is an important predictor of adherence to treatment and better outcomes.

Keywords: Abnormal uterine bleeding; Adenomyosis; Contraception; Heavy menstrual bleeding; Levonorgestrel-releasing intrauterine system; Uterine fibroids.