IVF Treatment - Laboratory procedures
Egg fertilisation and embryo culture
Collected eggs are taken to the laboratory and placed in ‘culture medium'. They are sorted (not all are equally mature or developed) and later that day the sperm, following preparation, is placed with them.
It is important to mention again that in classic IVF the prepared sperm and eggs are simply placed in a dish where fertilisation then occurs. For ICSI the semen requires extra special preparation.
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IVF |
ICSI |
An individual sperm is selected and, under very delicate microscopic control, the egg, itself requiring extensive preparation, is injected with this single sperm as shown to the left.
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Fertilisation |
Blastocyst |
The day following IVF / ICSI the scientists examine the eggs to determine if fertilisation has occurred. Plans will then be made for the embryo transfer usually within the next 24 - 48 hours (i.e. between 48 and 72 hours after egg collection). The timing of this procedure is NOT critical. At this time any extra suitable embryos may be cryopreserved (frozen) for later use. Some people may have their embryos cultured(grown) for an extra 2-3 days, using complex specific ‘sequential’ culture media and this is called Blastocyst Culture.
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PGD |
This allows further determination of the continued development and viability of the embryos. Some embryos may have cells removed for special analysis (Pre-Implantation Genetic Diagnosis - PGD) for chromosomal disturbances but this procedure is more costly and is only used in special instances.
Preimplantation Genetic Diagnosis in perspective
IVFAustralia believes Preimplantation Genetic Diagnosis is an exciting new technology that gives couples the option of testing embryos for serious inherited genetic disorders already affecting other family members. This has many advantages for a couple where they would find it hard to consider terminating an affected pregnancy after prenatal diagnosis at a later stage of pregnancy.
Worldwide researchers are questioning whether the same technology will allow improved embryo selection prior to embryo transfer, and hence improve pregnancy rates per cycle for all couples having IVF treatment. The small studies performed so far have not been of a large enough size or been designed to answer this question accurately.
We believe improved laboratory procedure and embryo culture methods will have the most dramatic effects on improving pregnancy rates. At present the cost to our patients, as well as the limitation of the screening on each embryo and the accuracy of that screening, means we are less confident that this has a real benefit for a large number of our patients.
Studies are taking place around the world to understand and refine this technique further and we will watch closely for evidence that this will improve patient care.
What is PGD?
Preimplantation Genetic Diagnosis is the earliest form of prenatal diagnosis screening carried out on a laboratory created embryo. It aims to prevent embryos carrying a genetic abnormality being transferred into the uterus. PGD is currently helpful if a couple has an increased risk of have a child with a specific genetic disorder.
How is PGD Performed?
At IVFAustralia if a couple is considering PGD, counselling is provided to ensure the appropriate time is taken to consider all of the implications of PGD. A woman will undergo an IVF-type procedure with ovarian stimulation to allow multiple egg collection. Fertilisation is carried out by ICSI and 3 days after fertilisation one or more cells are removed from the embryo. These cells can then be analysed for a specific inherited disorder or chromosome abnormality. Results are available on day 5 following fertilisation and only healthy embryos are transferred into the uterus.
Who Should Consider PGD?
At present PGD is an evolving technique in the world of fertility treatment. There is no current evidence to suggest PGD is appropriate screening for all embryos. We believe this technology should concentrate on screening embryos at high risk of being affected by inherited disorders.
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