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How embryo selection can increase pregnancy rates
Using the latest technologies, and innovations in the laboratory enable us to select the best embryo possible for transfer, giving our patients the best chance of having a baby. Embryo screening techniques such as blastocyst culture, time-lapse imaging and Preimplantation Genetic Testing are then brought together in our innovative new IVF Select programme, to produce outstanding success rates.
In the past embryos were left to develop for two or three days after egg collection before an embryo transfer took place. At this point the embryo contains around six to eight cells. Improvements in the laboratory now mean that the culturing of embryos can now be extended to five or six days, when the embryos will now have around 80 to 100 cells; they are now known as “blastocysts”.
Extending the culture to this stage gives an opportunity for the best embryos to be selected. Following fertilisation, some eggs may stop developing (“arrest”) or not pass the stage of a two- or three-day embryo. In the past these embryos may have been selected for transfer but now only embryos that reach the blastocyst stage will be considered. Research shows that a blastocyst embryo is more likely to implant in the womb and lead to a better chance of pregnancy.
Embryo selection can be helped by viewing their development in a specialist time-lapse incubator called an embryoscope. This piece of technology takes a photograph of the embryo every twenty minutes. Embryos placed in the embryoscope do not then need to be disturbed over this period and therefore not exposed to outside air conditions which could affect the embryo quality. Embryos develop stage by stage over time. By visualising the progress of embryo development over a period of five to six days (to blastocyst stage) the embryologist can select the best embryo for transfer.
Preimplantation Genetic Testing for Aneuploidy (PGT-A)
Most IVF cycles in the UK and across the world rely on an experienced embryologist selecting the best embryo for transfer based on its appearance. In recent years, an additional selection method has been introduced which allows embryos to be screened for chromosomal abnormalities (“aneuploidy”), called Preimplantation Genetic Testing for Aneuploidy (PGT-A). Following the development of embryos to blastocyst stage, a skilled embryologist will biopsy the embryo taking a few cells which will be sent to a specialist genetics laboratory for analysis. The embryos are then analysed using a screening method called “Next Generation Sequencing” (NGS) which identifies those that have a low risk of chromosome abnormalities, described as normal (“euploid”). Any embryos that are identified as euploid can then be prepared for transfer in a later cycle.
Our new IVF Select programme, developed by the team at the LWC London Bridge, brings together these techniques to provide a unique and pioneering IVF package used by only a handful of top IVF clinics in the world. IVF Select involves the freezing of all embryos in an IVF cycle, following development to blastocyst culture and time-lapse imaging. Prior to freezing, the embryos will be biopsied, and samples sent to a genetics laboratory for PGT-A. Embryos that are found to be euploid are then transferred, one at a time, in a later more natural Frozen Embryo Transfer cycle. Our IVF Select package includes up to two embryo transfers giving our patients two opportunities to achieve a pregnancy.
IVF Select can be particularly beneficial for patients who are between 35 and 42 years old, have had previous failed IVF attempts, are particularly interested in genetic testing or who want to become pregnant more quickly than through standard IVF. Our success rate for all ages show a cumulative ongoing pregnancy rate of 64%.