JBRA Assisted Reproduction 2025;29(Suppl.2 SBRA 2025):205
Poster Presentation
29^th Annual Congress of the SBRA. São Paulo/SP - Brazil, 2025
doi: 10.5935/1518-0557.20263880

P-193. Reduced oocyte competence after vitrification in women with endometriosis undergoing IVF: A retrospective cohort study

Mariana Lopes¹, Paula Ternus¹, Gabriella Mamede Andrade¹, Nilo Frantz¹, Marcos Iuri Roos Kulmann¹

¹ Nilo Frantz Medicina Reprodutiva - Porto Alegre - Rio Grande do Sul - Brasil

Objective: Endometriosis affects up to 10% of women of reproductive age and remains a major cause of infertility. In its severe forms, endometriosis involves the development of ovarian endometriomas, which harbor inflammatory mediators, proteolytic enzymes, and reactive oxygen species. This altered microenvironment is believed to impair both the quantity and quality of the ovarian reserve by promoting follicular fibrosis, disrupting steroidogenesis, and inducing molecular damage to the oocyte. Oocyte vitrification has emerged as a key strategy for fertility preservation in women with endometriosis, particularly prior to surgical intervention. However, the extent to which oocytes already compromised by endometriosis remain viable after vitrification is not fully understood. This study aimed to evaluate whether oocyte vitrification exacerbates impairments in oocyte developmental competence in patients with endometriosis undergoing IVF.
Methods: We conducted a retrospective cohort study including 818 IVF cycles performed between 2015 and 2024 at a single reproductive medicine center. All participants had surgically or clinically confirmed endometriosis according to the ASRM criteria, which include the presence of peritoneal implants, pelvic adhesions, and/or ovarian endometriomas. Cycles utilizing donor oocytes were excluded. We compared IVF outcomes between cycles using vitrified-warmed oocytes (n=13) and those using fresh oocytes (n=805). Controlled ovarian stimulation protocols and laboratory procedures were standardized across groups. Metaphase II (MII) oocytes were vitrified and subsequently warmed using the Cryotop^® Kitazato system. Embryo transfers were performed either at the cleavage (day 2-3) or blastocyst stage (day 5-6), in both fresh or frozen embryo transfer cycles. Blastocyst quality was assessed using the Gardner grading system, with top-quality embryos defined as having inner cell mass and trophectoderm grades of AA, AB, BA, or BB.
Results: Baseline characteristics were comparable between vitrified-warmed and fresh oocyte groups, including maternal age (35.4±4.9 vs. 36.1±4.2 years), anti-Müllerian hormone (AMH) levels (2.2±2.0 vs. 2.5±4.7 ng/mL), body mass index (BMI) (22.1±2.3 vs. 24.5±10.4 kg/m²), presence of multiple infertility factors (61.5% vs. 67.6%), and sperm concentration (27.8±26.4 vs. 31.8±35.2 million/mL), with no statistically significant differences observed (all p>0.05). Vitrified oocytes demonstrated a high post-warming survival rate of 95%. However, compared to cycles using fresh oocytes, those utilizing vitrified oocytes showed significantly lower blastocyst formation rates (29.6% vs. 52.4%, p<0.0001) and top-quality blastocyst rates (20.9% vs. 40.3%, p<0.001). The proportion of embryo transfers performed at the cleavage stage (23.1% vs. 17.2%) versus the blastocyst stage (76.9% vs. 82.8%) and the average number of embryos transferred per cycle (1.42 vs. 1.40) were similar between groups. Although not statistically significant, there was a trend toward lower live birth rates in the vitrified oocyte group compared to the fresh oocyte group (23.1% vs. 31.5%, p=0.7645).
Conclusion: Blastocyst formation and the rate of top-quality blastocysts were reduced by approximately 50% in women with endometriosis undergoing IVF using vitrified-warmed oocytes. Additionally, embryo transfers from vitrified oocytes showed a non-significant trend toward lower live birth rates. These findings suggest that oocytes from women with endometriosis may be more vulnerable to cryodamage, potentially reducing the efficacy of vitrification as a fertility preservation strategy in this population. Larger, well-designed prospective studies with appropriate control groups are needed to confirm these results and support the development of individualized treatment approaches.