Background: Advances in fertility preservation have expanded reproductive options for children, adolescents, and young adults undergoing gonadotoxic cancer treatment. Ovarian tissue oocyte in vitro maturation (OTO-IVM) enables recovery and maturation of immature oocytes obtained during ovarian tissue cryopreservation or oophorectomy without hormonal stimulation or treatment delay. This approach may increase fertility preservation potential by utilising oocytes that would otherwise be discarded.
Aim: To determine the clinical, demographic, and laboratory factors associated with OTO-IVM outcomes and oocyte quality.
Methods: A total of 355 metaphase II (MII) oocytes from 53 patients were analysed using an international deidentified clinical dataset. Associations between patient, treatment, and laboratory characteristics and oocyte morphology were assessed using Pearson's χ² and Fisher's exact tests. Receiver operating characteristic analysis and binary logistic regression were performed to identify factors associated with oocyte dysmorphisms while adjusting for age. Additionally, 106 immature oocytes donated for research by oncofertility patients at The Royal Women's Hospital underwent biphasic capacitation in vitro maturation (CAPA-IVM) culture for 48 hours before maturation assessment.
Results: OTO-IVM enabled successful retrieval and maturation of immature oocytes from ovarian tissue specimens. Ovarian cancer was associated with a 2.21-fold increased likelihood of abnormal oocyte morphology. A history of gynaecological surgery was associated with dark cytoplasm (p=0.002; OR 16.65; 95% CI 1.98-140.24), while patients aged >35 years were more likely to develop small polar bodies (OR 2.72; 95% CI 1.20-6.18). Transportation of ovarian tissue on ice increased the likelihood of cytoplasmic granularity (OR 2.57; 95% CI 1.30-5.18). Biphasic CAPA-IVM significantly reduced large polar bodies compared with monophasic IVM (p=0.034). Maturation was achieved in 43.4% (23/53) of donated immature oocytes.
Conclusion: OTO-IVM may enhance fertility preservation by converting ovarian tissue into an additional source of mature oocytes. These findings support integration of OTO-IVM into fertility preservation pathways and highlight factors influencing oocyte quality.