Rescue In Vitro Maturation of Immature Oocytes to Improve Oocyte Utilization in IVF/ICSI Cycles

Purpose : This study aimed to enhance the utilization of immature oocytes retrieved during IVF/ICSI cycles through rescue in vitro maturation (R-IVM). Methods : A retrospective analysis was performed on patients with immature oocytes (at the MI or GV stage) during IVF/ICSI cycles between December 2023 and March 2025. Oocyte retrieval was conducted 36–38 hours post-trigger. In the IVF group, cumulus cells were removed 4–5 hours post-insemination to assess extrusion of the second polar body. For ICSI, denuded oocytes were evaluated 1–2 hours after denudation. Immature (MI/GV) oocytes were cultured in in-house formulated IVM medium droplets. Matured oocytes (MII) were fertilized via ICSI within 16–40 hours and cultured in a time-lapse incubator. Outcome measures included maturation, fertilization, cleavage, top-quality embryo, and clinical pregnancy rates. Results : A total of 77 MI/GV oocytes from 23 patients were included. The maturation rate was 75.32% (58/77). The overall fertilization rate was 65.52% (38/58), with 48.28% (28/58) exhibiting normal (2PN) fertilization. The cleavage rate among 2PN zygotes was 96.43% (27/28). Abnormal fertilization and degeneration rates were 17.24% (10/58) and 10.34% (6/58), respectively. The top-quality D3 embryo rate was 29.63% (8/27). Nine transferable embryos were obtained: two fresh transfers resulted in clinical pregnancies (one live birth), and one frozen transfer led to a live birth. Conclusions : R-IVM improves the utilization of immature oocytes in IVF/ICSI cycles and can enhance clinical pregnancy outcomes.