Double ionophore application may improve rates of blastocyst formation and clinical pregnancy in cases of failed single application

Published:November 17, 2021DOI:


      Research question

      Does a double ionophore application improve the outcome of cycles in which single ionophore application proved unsuccessful?


      This retrospective intervention study (duration 4.5 years) included 79 patients with suspected chronic failed oocyte activation (0-30% fertilisations) and/or embryo development (developmental arrest, 24 h developmental delay, blastulation rate of <15%) in both preceding cycles, in first one without ionophore and second one with single ionophore treatment. Within the study period, all patients with failed ionophore treatments (single applications of ready-to-use calcimycin for 15 min) were offered an adapted protocol in the subsequent cycle (study group) in which the same ionophore was applied twice (separated by 30 min). Thus, the only difference between the protocols was the number of calcimycin exposures. Tests for paired data (control and study cycle) were used to reduce the effect of confounders.


      The overall fertilisation rate did not differ between the study and control groups. However, the cleavage and blastocyst formation rates improved significantly in the study cycles (P<0.05). A significant increase in the rates of implantation (P<0.01), and biochemical (P<0.001), and clinical pregnancy (P<0.05) in the study group was also noted. The live birth rate in the study group was 38.2% and all 32 babies born were healthy.


      This is the first study to document evidence that double ionophore application may improve the rates of blastocyst formation and clinical pregnancy in cases of failed single ionophore treatment, irrespective of whether the ionophore was used to overcome fertilisation or developmental problems. Fertilisation was only increased in cases with a history of reduced oocyte activation. Since single ionophore treatment was used in only one previous cycle it cannot be ruled out that some improvement in clinical outcomes would also have been achieved with re-using single instead of double ionophore treatment in the subsequent attempt.

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      Thomas Ebner has published more than 160 papers and book chapters as first and co-author. Research interests include non-invasive IVF selection processes, andrology, vitrification, culture media and time-lapse imaging. He was certified as a senior clinical embryologist by ESHRE in 2008. He was executive board member of Alpha and ESHRE.
      Key message
      In cases where single ionophore application failed to increase intracellular calcium, double ionophore application may improve cleavage rates, blastocyst formation, and clinical pregnancy in patients with poor prognoses.