P-376 Oocyte accumulation program in young women at high risk of ovarian injury due to endometriomas or benign ovarian tumors: intermediate results from a prospective study

Abstract Study question Is oocyte accumulation for fertility preservation a good option for young women with benign ovarian tumors (BOT) in terms of feasibility, compliance and efficiency? Summary answer Oocyte accumulation may be safely offered to young women with BOT at high risk of ovarian reserve impairment to optimize the number of cryopreserved oocytes. What is known already BOT, i-e endometriomas, sero-mucinous or dermoid cysts, are at high risk of ovarian reserve injury, due to iterative surgeries, cysts “itself” and recurrence risk. Endometriomas are particularly challenging due to toxic effects on surrounding ovarian parenchyma, surgical difficulties and risk of recurrence. Oocyte vitrification is now recognized as the first-line option for fertility preservation in post-pubertal women. It has been shown in retrospective studies that oocyte accumulation may be the best option to reach enough vitrified oocytes. However, the adherence of patients to such a program, the efficiency and safety remains poorly investigated. Study design, size, duration OFBOT (Oocyte Freezing for Benign Ovarian Tumors) is a prospective single-center observational study, performed from December 2019 to December 2023, where 156 young women (18-35 yo) with personal history of BOT were offered an oocyte accumulation program. The primary outcome was to evaluate the number of cryopreserved metaphase II (MII) oocytes per cycle and after accumulation and the determinants associated with this number. Secondary outcomes included reutilization rate and reproductive outcomes. Participants/materials, setting, methods 156 women aged 28.5±4.8, with a personal history of BOT and high risk of ovarian reserve impairment were recruited on the following criteria: large (≥5) cm or multiple ovarian cysts, history of oophorectomy or ≥ 1 ovarian surgery were included. Women were free to undergo up to 3 cycles of controlled ovarian hyperstimulation to optimize the number of cryopreserved oocytes. A total of 253 cryopreservation cycles were performed in our tertiary-care center. Main results and the role of chance 122 patients of 156 (78.2%) had a history of ovarian surgery prior to fertility preservation. 88 (56.4%) patients had endometriomas, 45 (28.9%) dermoid and 23 (14.7%) cystadenomas. Median AMH level before ovarian stimulation was 11.9 (7-19.9) pmol/l. To date, all women underwent at least one cycle, 79 (50.6%) two and 19 (12.2%) three cycles. The mean number of vitrified MII oocytes per patient after accumulation was 7.5±5.2. 49.6% of patients had more than 8 meta II oocytes after 2 cycles. BMI, AMH levels, number of surgeries, hormonal treatment and endometriosis were significantly correlated to meta II oocytes number. After multivariate analysis, only the presence of endometriomas (OR 0.78, 95%CI 0.68-0.90, p < 0.001) and ovarian surgeries (OR 0.82, 95%CI 0.68-0.97, p = 0.023) remained significant. One case of mild ovarian hyperstimulation and one case of ovarian torsion requiring surgery were registered. To date, 18 patients (11.5%) asked for reutilization. 9 pregnancies (50%) were achieved, with three live births and six ongoing pregnancies. There was no significant difference on meta II oocytes between endometriosis group versus dermoid/sero-mucinous group despite a younger age and higher number of ovarian surgeries and oophorectomies in the latter. Limitations, reasons for caution This study concerns a very specific subgroup of young women with extensive surgical history and high risk of ovarian reserve injury. This is an interim analysis that does not yet allow conclusions to be drawn about reutilization rates and further fertility. Wider implications of the findings This is the first prospective program of oocyte accumulation including all histotypes of BOT. This will give the opportunity to investigate feasibility, safety and efficiency of the procedures and further allow to drawn evidence-based fertility preservation strategies with cost-effectiveness evaluation in this specific subgroup of women. Trial registration number Yes