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

Abstract Research question Does a double ionophore application improve the outcome of cycles in which single ionophore application proved unsuccessful? Design 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 Results 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 Conclusions 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.