F14Functional ovarian cysts during the use of levonorgestrel releasing intrauterine system

Background We wanted to study the effect of a levonorgestrel‐releasing intrauterine system (Mirena) on ovarian morphology in hypermenorrheic women. Methods 236 women suffering from menorrhagia participated in this study. The patients were randomized to two groups: 118 women received mirena and 106 went through hysterectomy. All the subjects were 35–49‐year‐old. Transvaginal ultrasound was performed at baseline, and both six months and one year after mirena insertion/hysterectomy. Results An ovarian cyst of more than 30 mm in diameter was detected in 13 patients at baseline. The mean diameter of the cyst was 34 mm (SD 8, range 32 × 19 to 62 × 28 mm). At six month control 19 patients had an ovarian cyst of a diameter more than 30 mm and at one year follow‐up an ovarian cyst was detected in 23 and two cysts in two patients using Mirena. In the hysterectomized group the number of ovarian cysts were 3 and 8, respectively. The mean size of the ovarian cysts was similar in both groups. None of the ovarian cysts required surgical intervention during the follow‐up period. At baseline 110 patients (46.6%) were diagnosed as having uterine fibroids with a mean diameter of 22 mm. The size of uterine fibroids did not increase during the study period. Conclusion Functional ovarian cysts are more frequent in women using mirena compared to hysterectomized women of similar age. However, the ovarian cysts observed during the study did not lead to surgical intervention.