A blastocyst transfer involves transferring an embryo on day five, instead of day three as in a normal embryo transfer. It's at this blastocyst stage of development that an embryo would naturally move out of the fallopian tube and into the uterus.
A blastocyst transfer can significantly increase the chances of a positive implantation, and therefore a successful pregnancy. For women under the age of 35, using fresh blastocyst created with their own eggs, the percentage of cycles that result in a live birth can be as high as 60%. This rate drops down to 33% for women over the age of 40.
The actual blastocyst transfer procedure is identical to a normal embryo transfer, but with the embryos being allowed to develop for five to six days before transfer. The patient will not be aware of any noticeable differences.
Blastocyst transfer is recommended for younger women who have a good chance of successful in vitro fertilisation treatment. The method can increase the likelihood of a successful outcome yet further. The procedure is also useful in cases where good quality embryos have failed to implant in the womb in previous IVF cycles.
However, blastocyst transfer is less suitable for women who produce fewer than normal healthy eggs. This is because only 50% of embryos may develop to the blastocyst stage. Waiting until this later stage may result in zero chance of pregnancy, when a normal embryo transfer could have proved successful.
Another risk of blastocyst transfer is a greater incidence of multiple births. However, this can be addressed by reducing the number of blastocysts during transfer.
The number of embryos available for freezing is also reduced following a blastocyst procedure. This can adversely affect the possibility of having frozen embryo transfer at a later date.
It's also worth noting that blastocyst transfers will typically cost more than standard IVF treatment. Prices can vary considerably between clinics but it should cost no more than an extra few hundred pounds.
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