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  6. Embryo culture

Normally fertilized oocyte
(2 pronuclei)
A cultured egg is usually inspected under the microscope at 18 hours after placing it with sperm, and then again about 30 hours later. The inspection at 18 hours is important, because this is a milestone time when usually the first signs of normal fertilisation can be observed. Normally the embryo will have divided into two or four cells in 48 hours, although occasionally growth may be somewhat more advanced. Before an embryo is transferred back to the womb, we make sure it appears normal. If there is doubt about this we may wait a further 24 hours before taking a decision whether we should transfer it or not (With current scientific evidence it is not detrimental to the outcome if embryo transfer takes place on day 2 or 3 after fertilization). Our team is curretly researching the hypothesis that a late transfer on day 4 or 5 after fertilization may offer the benefit of choosing the best embryo.

Embryos that seem seriously abnormal are not transferred. They are either discarded if that is the couple's wish, or alternatively studied to see if we can find out why they grew abnormally.

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