Impact of Oocyte Denudation Timing on Fertilization Rates and Blastocyst De-velopment: A Systematic Literature Review

Background: There is ongoing debate regarding the timing of denudation during In-vitro Fertilization (IVF) or Intra Cytoplasmic Sperm Injection (ICSI) procedures because of its impact on oocyte quality and treatment outcomes. A process that involves both en-zymatic treatment and mechanical stripping can influence oocyte quality and maturity. For ICSI, denudation helps assess oocyte ma-turity and quality, while in IVF, cumulus cells are typically removed after fertilization to evaluate its success. Yet, the optimal timing for denudation is still not well-defined, necessitating further studies to understand its impact on assisted reproductive technology (ART) results.

Purpose: This review aims to assess how the timing of denudation affects fertilization rates and the formation of blastocysts in ART procedures.

Methods: We conducted a systematic review of literature published between 2003 and 2024. A total of 32 articles were reviewed, and 12 studies that met the inclusion criteria were included. These consisted of original published research reporting on fertilization rates, pregnancy rates, embryo quality, and live birth rates. Animal studies were excluded from this review.

Results: This study shows that with denudation exceeding more than 5 hours, fertilization rates decline significantly, reaching as low as 27.3% at the 8-hour mark. The objective for the oocyte denudation timing interval from oocyte retrieval to ICSI is less than 5 hours to enhance the chances of fertilization. However, limited data on blastocyst formation are available; therefore, further studies are required to better understand the overall impacts on fertilization, embryo development, and clinical pregnancy rates.

Conclusion: Although the best denudation timing of oocytes is still unclear in ART, a pre-incubation of cumulus oocyte complex (COCs) for one to four hours post ovum pickup may be beneficial. An interval of more than four hours in COC denudation might be harmful. It is necessary to conduct further studies with upgraded protocols in order to create evidence-based guidelines to improve oocyte maturation, fertilization, and blastocyst development.