Rescuing Fertilization Failure in ICSI: A Narrative Review of Calcium Ionophore Activation, PLCζ Testing, and Embryo Morphokinetics

Abstract

Fertilisation failure following intracytoplasmic sperm injection (ICSI) is a significant challenge in assisted reproductive technology (ART), particularly in the absence of an identifiable cause. Artificial oocyte activation (AOA), typically with calcium ionophores, has emerged as a potential solution in scenarios characterised by a deficiency of phospholipase C zeta (PLCζ). This narrative review consolidates the latest clinical and experimental data regarding the application of calcium ionophores for oocyte activation, the significance of PLCζ testing in instances of unexplained fertilisation failure, and the impact of AOA on the morphokinetics and developmental potential of embryos. AOA has demonstrated an enhancement in fertilisation, cleavage, and pregnancy outcomes in specific patient populations, including individuals with diminished ovarian reserve or those who have previously attempted conception unsuccessfully. Although AOA appears to have no impact on embryo morphokinetics, certain studies indicate slight alterations in early cleavage features. The available statistics indicate that there are no significant safety concerns about outcomes for babies. This finding underscores the significance of tailored ART methodologies that incorporate molecular diagnostics and targeted AOA therapies. It emphasises the necessity for additional prospective trials to enhance patient selection and long-term safety surveillance.

Keywords: artificial oocyte activation; assisted reproductive technology; calcium ionophore; calcium signalling; embryo morphokinetics; fertilisation failure; intracytoplasmic sperm injection; oocyte activation deficiency; phospholipase C zeta; time-lapse imaging.