Dual calcium ionophore oocyte activation after ICSI in globozoospermia: fertilization and cumulative live birth outcomes.

RESEARCH QUESTION: Can dual calcium ionophore artificial oocyte activation (AOA) after intracytoplasmic sperm injection (ICSI) overcome fertilization failure and support live birth in couples with globozoospermia and prior total fertilization failure (TFF)?

DESIGN

This retrospective cohort included 33 couples with globozoospermia and documented TFF in previous ICSI cycles without AOA who underwent 55 ICSI-AOA cycles between 2013 and 2024. AOA comprised two 8 min exposures to 10 µmol/l A23187 separated by an 8 min interval in fresh culture medium. Primary outcomes were fertilization rate and live birth rate per embryo transfer. Secondary outcomes included blastulation rate, clinical pregnancy rate per embryo transfer and cumulative live birth rate per couple.

RESULTS

Among 560 metaphase II oocytes, 402 fertilized normally (71.8%); 317 developed into day 3 embryos (78.9% of 2 pronuclear zygotes) and 195 into blastocysts (48.5%). Fifty-eight embryo transfers involving 142 embryos produced 41 gestational sacs (implantation rate 28.9%), 34 clinical pregnancies (58.6% per embryo transfer), 8 miscarriages (23.5% of clinical pregnancies) and 26 deliveries with at least one live birth (44.8% per embryo transfer), resulting in 35 live-born infants. Seven couples had two live-birth deliveries; overall, 19 of 33 couples achieved at least one live birth (cumulative live birth rate 57.6%). In exploratory unadjusted analyses, the median fertilization rate was higher with ejaculated than surgically retrieved spermatozoa (80.0% [IQR 70.2-86.0%] versus 60.0% [IQR 46.5-73.2%]; P = 0.009).

CONCLUSIONS

Dual calcium ionophore AOA after ICSI in couples with globozoospermia and prior TFF was associated with adequate fertilization efficiency, satisfactory embryo development competence and a favourable cumulative live-birth rate. Prospective studies are warranted to confirm optimal activation strategies and long-term offspring safety.