In principle, the transferral of fertilised egg cells can take place two to six days after egg retrieval. A prolonged culture phase can help to identify the embryos with the best potential for implantation. The development of each embryo throughout the culture phase can be observed in particular detail with the use of video recording. The images can then be evaluated objectively on the basis of characteristic stages of cell division. Of course, this technique is most successful when a sufficient number of fertilised eggs are available. In accordance with the legal requirements in Germany, the number of embryos cultured is individually adjusted according to the couple’s circumstances but may not exceed six. If there are more “promising” embryos than the anticipated number for transfer, these can be cryopreserved and thus stored for further treatments. The time-lapse procedure can also be useful in cases where several prior embryo transfers have not led to pregnancy. The continuous observation of the development under culture conditions can help to reveal any abnormalities.
The time-lapse procedure can help to select the most promising embryos for transfer.