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extended culture / embryo transfer

Traditionally, embryo transfer for IVF was performed 2 or 3 days after insemination and the embryos had grown to 2-4 cells (day 2) or 6-8 cells (day 3). The process used to identify the most suitable embryos for transfer at this very early stage of their development relies mainly on criteria relating to their appearance.

Research, if conducted properly, has found that there is a difference in pregnancy rates between early stage and late stage embryos. Extended culture appears useful where there are more than 3 developing embryos. It appears to aid in the selection process, as not all embryos have the potential to develop either in culture or in the uterus.

Culture Media

New culture media have been developed to extend the period of embryo growth outside the body to the latest stage of pre-implantation development.

By providing a culture system that allows embryos to grow successfully for longer periods outside the body we are able to select embryos on the basis of ability to continue developing.

In natural conception the embryo continues to develop until approximately day seven post fertilisation and will then attempt to implant into the endometrium.

With extended culture the embryos are replaced into the uterus well before implantation should occur, giving the embryos every opportunity to continue development

Embryo transfer

In some patients the embryo transfer is not done because all of the embryos fail to grow appropriately. The risk of not achieving an advanced stage embryo transfer is higher for patients who do not respond well to ovary stimulation and produce only a few eggs, or patients who have few embryos.

There is also a subset of women whose embryos do not develop beyond the early embryo stage. Hence, extended culture can potentially reveal information on why a pregnancy has not been achieved in the past.

As there is an increase in the implantation rate with extended culture embryos we advocate the transfer of a single embryo to avoid the complication of a twin pregnancy. However, your Monash IVF clinician will help you make a decision on how many embryos to transfer.

The extended culture technique is now available as a clinical embryology technique at Monash IVF. Your doctor will advise you of the treatment options available to you and whether this technique is suitable for you.