Pathological findings associated with the presence of a mirena intrauterine system at hysterectomy.

The Mirena intrauterine system (IUS) has improved the options available to women with menorrhagia. However, in some women, IUS treatment fails to reduce menstrual flow, and surgical treatment, including hysterectomy, is necessary. We have reviewed the histopathological findings on the uteri of 44 women undergoing hysterectomy because of menorrhagia after unsuccessful IUS treatment to assess whether a potentially unresponsive cohort could be identified. A retrospective review of 44 hysterectomy specimens was performed between October 1999 and April 2006 on women who underwent unsuccessful treatment of menorrhagia with the IUS. The patients' ages ranged from 30 to 53 years (median age, 43 years; all were premenopausal). Most women (60%) had the expected appearance of atrophy of the endometrial glands and pseudodecidual stromal reaction. Thirty hysterectomy specimens contained benign leiomyomata with associated reduced reactivity in the uterine cavity and incomplete suppression of the endometrium. In some cases (n = 10), the fibroids had displaced the IUS in the uterine cavity. Fourteen specimens showed adenomyosis, of which 8 also contained fibroids. In addition to leiomyomas, 1 specimen had an atypical polypoid adenomyoma and 1 had a benign adenomatoid tumor. Two specimens had endometrial hyperplasia for which the IUS was unsuccessful in controlling bleeding. Two specimens showed intrauterine misplacement of the IUS. Only 6 women (13.6%) had no histological abnormalities. Most women (86%) undergoing hysterectomy because of abnormal uterine bleeding with a Mirena IUS in situ had uterine abnormalities, as revealed by pathological review. Although recent reports have indicated that the IUS can be used successfully in the treatment of menorrhagia due to uterine fibroids, most cases of hysterectomies in this series after failed IUS suppression of menorrhagia contained uterine fibroids.