Histological analysis of (antral) follicle density in ovarian cortex tissue attached to stripped endometriomas

Abstract

Purpose: When resecting endometriomas with the stripping technique, in the majority of cases, a thin line of adjacent ovarian cortex is attached to the endometrioma. In this study, we performed histological analysis to determine (antral) follicle density in the ovarian cortex tissue attached to stripped endometriomas and assessed patient- and surgical characteristics that could affect this.

Methods: Histological slides of previously removed endometriomas were assessed. Follicles in the attached ovarian tissue were classified according to maturation, and follicular density was determined. Immunofluorescent staining of antral follicles in a subset of endometriomas was also performed.

Results: In 90 out of 96 included endometriomas (93.7%), ovarian tissue attached to the cyst wall was observed. One thousand nine hundred forty-four follicles at different maturation stages were identified (3 follicles/mm³). Follicle density was negatively associated with age (p < 0.001). Antral follicles (< 7-mm diameter) were present in the ovarian tissue attached to 35 endometriomas (36.5%) derived from younger patients compared to endometriomas where none were detected (30 versus 35 years, p = 0.003). Antral follicle density was 1 follicle/mm³. Based on immunofluorescence, healthy antral follicles were identified in two out of four examined endometriomas.

Conclusions: Ovarian tissue attached to stripped endometriomas holds potential as a non-invasive source for antral follicles. In theory, application of IVM could be an interesting alternative FP option in young patients with endometriomas who undergo cystectomy in order to transform the surgical collateral damage to a potential oocyte source. Our results encourage future research with fresh tissue to further assess the quality and potential of these follicles.

Trial registration: Clinical Trials.gov Identifier: B21.055 (METC LDD), date of registration 12-08-2021, retrospectively registered.

Keywords: Endometrioma surgery; Follicle density; In vitro maturation; Ovarian endometriosis.