Blastocyst Transfer

12.3.11

surviving blastocysts available for Background Disadvantages of blastocyst transfer have normal chromosomes. transfer A blastocyst is an embryo that However, there is no guarantee that It is possible that up to 15% of consists of around 100 cells. It is at embryos that do develop to the patients will not have a blastocyst the blastocyst stage of development blastocyst stage are genetically available to transfer. In these cases (5 days after fertilization) that an normal. embryo would normally move out of the embryos have failed to develop to the uterine tube and into the uterus. the blastocyst stage. It has been shown that only 50% of embryos will Once in the uterus, the blastocyst In contrast to embryo transfers that develop to the blastocyst stage. starts to attach to the uterine lining in take place 2 or 3 days after egg There is however, evidence that if no a process known as implantation. collection and fertilization, blastocyst embryos have developed to the 8- transfer places the embryo into the cell stage on day 3 of culture, there is uterus at a later stage (day 5 or 6) no advantage gained by extending In IVF/ICSI cycles embryo transfer which approximates the time an culture to the blastocyst stage. This has been routinely performed on day embryo would normally arrive in the research shows that day 3 transfers 2 or 3 of culture when an embryo uterus. This may allow a better in these cases results in a 30% consists of 4 to 8 cells. This tradition harmony between embryo pregnancy rate compared to 0% if arose from the idea that in vitro development and the uterine culture is extended to the blastocyst culture for extended periods might be environment. harmful to the future growth of the stage. To avoid the disappointment embryo. This problem has now been of having no blastocysts to transfer on day 5 or 6, we advise that when overcome by the development of Using specially developed culture no 8-cell embryos have developed by culture media that takes into account media, a higher implantation rate has day 3, the best available embryo is the changing nutritional been observed following transfer of transferred on this day rather than requirements of the embryo as it blastocysts (50%), compared to day extending culture to the blastocyst develops. 3 (25%) embryo transfer. Research stage. shows that pregnancy rates after blastocyst transfers are either Research shows that human increased or stay the same, when The number of embryos suitable for embryos can now be cultured to the compared to day 2 or 3 transfers. freezing is reduced following blastocyst stage without reducing This research suggests that blastocyst culture. As a implantation and pregnancy rates. blastocyst transfer should enable consequence, the possibility of transfer of only one embryo without frozen embryo transfer should the reducing pregnancy rates. Benefits of blastocyst fresh transfer be unsuccessful is also transfer reduced. There is now evidence from research Concept’s results now show that the studies that although embryos may pregnancy rates are similar between have a normal appearance, up to day 3 and blastocyst transfers, but a 70% can be chromosomally reduction in the number of high-order abnormal. Studies also show that the (triplets etc) multiple pregnancies majority of embryos that fail to was evident in the blastocyst transfer develop past the 8-cell stage are group. chromosomally abnormal, so that, extending culture to the blastocyst stage may mean that more of the

Version 6 May 2015 Authorised by Peter Burton Page 1 of 2 Page 2 of 2

Patients who use the blastocyst Another study showed that there transfer procedure cannot undergo were no overall differences in birth GIFT. It can only be performed in weight observed between infants association with IVF/ICSI (Reference born after blastocyst transfer IVF/GIFT Information Sheets). compared to those born after natural conception. Interestingly, birth

weights of girls born after transfer of There is an extra fee for couples who frozen-thawed blastocysts were wish to use blastocyst transfer above slightly higher than the normal what is normally charged for population (3.416g vs 3.331g IVF/ICSI. Please speak to the Nurse respectively). This analysis also Coordinator who will discuss this with showed that blastocyst transfer can

you before you commence potentially alter the sex ratio with A blastocyst on day 5 treatment. more boys born after fresh blastocyst Patients likely to benefit transfer. The transfer of blastocyst that had been frozen and thawed did from blastocyst stage not alter the sex ratio (51.9% boys: transfer 48.1 girls). Those patients at risk of multiple pregnancy. For example, patients 35 Management of a blastocyst and under with 6 or more embryos. transfer cycle Blastocyst transfer will normally take

place on day 5 or 6 after egg Those patients who have had collection depending on blastocyst repeated implantation failures (3 or development. In the situation where more). In these cases blastocyst no 8-cell embryos are available on culture may offer the advantage of day 3, a transfer may occur on this A hatched blastocyst allowing transfer of embryos that are day. more likely to be genetically normal,

and therefore have better chance of developing into a successful Should you require any further pregnancy. information please contact the A blastocyst is formed Scientific Director at Concept. when an embryo reaches Birth outcomes following the 5 to 6 day blastocyst transfer developmental stage and An analysis of over 500 pregnancies is a sphere consisting of an and births showed no increase in the incidence of abnormalities following inner cell mass, an internal transfer of blastocysts. In this fluid filled cavity, and an analysis the number of abnormalities outer layer of cells (the was 11/510 (2.3%) and the majority trophoblast). of these were trisomies (abnormal Contact Us number of chromosomes). These abnormalities were associated with 218 Nicholson Road advanced maternal age (37 – 43 The inner cells mass will Subiaco WA 6008 years). form the fetus and the trophoblast cells will form Telephone: (08) 9382 2388 the placenta. A blastocyst Facsimile: (08) 9381 3603 must hatch (from the zona pellucid) before it can attach to the lining of the [email protected] uterus during implantation www.conceptfertility.com.au which occurs 6 to 7 days after fertilization.