F) Embryo replacement


Embryo replacement (ER) is normally carried out when the embryos are usually at day 3, but can be anytime between 3 and 6 days old. The exact time will depend on the quality of the embryos. As the embryologists have been nurturing the couple's embryos right from Day 1, they are able to determine the most suitable day for replacement of the embryos back into the womb. The embryologist is also able to select the best quality embryos for transfer.  Any excess embryos that are not replaced into the womb are frozen for future embryo replacement. Only good healthy embryos are frozen.

Embryo replacement is a painless procedure and no anaesthetic or sedation is required. All we ask is that you try to have a full bladder during the procedure in order to ensure a smooth transfer. This is one of the most important parts of the programme. The embryos are placed gently back into the womb through the cervix using a very thin, soft plastic tube. This procedure will feel just like having a Pap smear.

Usually between 2 and 4 embryos are replaced: if you are very young (less than 35 years of age) only two are replaced as the chances of multiple pregnancy is higher if more embryos are replaced. However, the average number replaced if the woman is over the age of 35 is 3 embryos. Occasionally, but only under special circumstances, four are replaced. These limits are determined by the Ministry of Health, Singapore. The chances of pregnancy increase with the number of embryos transferred but so does the incidence of multiple births, hence the need for the control. Your Doctor will decide what is the optimal number for you. The period that the embryo is cultured in the laboratory may be adjusted to suit the different needs of each patient but in practice, the minimum is 3 days. With your permission, any extra embryos that are not replaced will be frozen for future use only if they are of sufficiently good quality.

After the replacement, you will be asked to rest in bed for a few hours after which you can go home. Whilst at home, you should not plan to do anything strenuous for the following few days so as not to disturb the embryos. Hormonal injections will also be given to you to support the anticipated pregnancy, if the risk of Ovarian Hyperstimulation is minimal (see below). Blood tests are performed 18 days after egg collection to confirm pregnancy. Some bleeding from the vagina can occur even though you are pregnant, so it is important to do this test even if you think you are having your period.

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