Pathology of the NovaSure (radio-frequency) impedance-controlled endometrial ablation system

The widespread use of increasingly novel diagnostic and neoadjuvant therapeutic modalities necessitates that contemporary pathologists familiarize themselves with the spectrum of tissue derangements that may be seen in the eventual surgical specimens. In the management of endometrial lesions, for example, a variety of endometrial ablation technologies, such as cryosurgery, balloon therapy, microwave, hot circulating saline, and bipolar impedance technology, have been introduced in the past decade and are being utilized with increasing frequency. We describe herein pathologic changes associated with one such technology, the NovaSure impedance-controlled endometrial ablation system. The US Food and Drug Administration approved NovaSure in 2001 for ablation of the endometrial lining in premenopausal women with menorrhagia. The ablation is accomplished by the delivery of radio-frequency energy for a period of approximately 90 seconds through a device inserted transcervically into the endometrial cavity. Our patient, a 54-year-old with menorrhagia, had undergone the NovaSure ablative treatment 38 days prior to her eventual hysterectomy. The resultant changes were quite distinctive: in a uterine wall that was 20 to 30 mm thick, a 3- to 6-mm-thick, hyalinized, subendometrial bandlike zone was apparent throughout the uterus even on macroscopic examination of the slides. This zone was sharply demarcated from the subjacent myometrium and from the endometrium; the latter displayed severe stromal fibrosis, some myxoid change, and sparse glands that were largely confined to the basalis. Paradoxically, scattered aggregates of stromal cells in the endometrium remained relatively viable. Adenomyotic aggregates and leiomyomata in the myometrium beneath the hyalinized zone were unaffected by this treatment. Practitioners evaluating hysterectomy specimens should be aware of changes such as those described herein, not only to better understand the specimens they evaluate but to avoid potentially misinterpreting grotesque alterations caused by benign processes.