This study aims to evaluate the feasibility and tissue selectivity of a novel surgical technology, the Cavitron Ultrasonic Surgical Aspirator (CUSA) Clarity, in the management of ovarian endometriomas. Ovarian endometriomas are cysts caused by endometriosis that can damage ovarian reserve when treated by conventional surgery. In this study, ovarian cyst wall specimens are examined ex vivo using different Tissue Select settings of the CUSA device. Histopathological analyses are performed to determine whether endometriotic epithelium can be selectively removed while preserving normal ovarian tissue. The findings may contribute to developing fertility-preserving surgical approaches for women with endometriomas.

Endometriomas are one of the most common manifestations of endometriosis and are frequently associated with infertility. Conventional cystectomy often results in inadvertent removal of normal ovarian tissue, which may reduce ovarian reserve. To address this issue, the Cavitron Ultrasonic Surgical Aspirator (CUSA) Clarity system, particularly with the Tissue Select mode, has been proposed as a tissue-selective surgical device.

In this observational histopathological study, ovarian endometrioma wall specimens obtained during surgery are divided into multiple parts. Each part is subjected to ex vivo treatment with the CUSA Clarity device at different Tissue Select settings (0-4). The treated samples are fixed, paraffin-embedded, and stained with hematoxylin-eosin and immunohistochemical markers (e.g., cytokeratin 7, CD10). Pathologists evaluate the extent of removal of endometriotic lesions and preservation of normal ovarian stroma.

The primary objective is to assess whether endometriotic epithelium can be selectively removed while sparing ovarian stromal tissue. Secondary objectives include evaluation of the depth of tissue removal and the presence of residual lesions at unscraped margins. The results are expected to provide histopathological evidence supporting the potential clinical application of CUSA in fertility-preserving surgery for ovarian endometriomas.

Inclusion Criteria:

• Female patients diagnosed with ovarian endometrioma who undergo surgical treatment (cystectomy or adnexectomy) at Kanazawa University Hospital between January 1, 2025, and March 31, 2027.
• Written informed consent obtained prior to study participation.
• Age ≥ 20 years at the time of consent.
• For patients with previously stored endometrioma specimens under a broad consent, additional written consent for participation in this study will be obtained.

Exclusion Criteria:

• Patients with suspected malignancy based on preoperative imaging.
• Patients judged by the attending physician to be unsuitable for participation in this study for any reason.

Women aged 20 years or older diagnosed with ovarian endometrioma and treated surgically at Kanazawa University Hospital. Surgically resected ovarian endometrioma specimens are used for ex vivo histopathological evaluation of selective lesion removal using the CUSA® Clarity device.