• Down regulation - Firstly, the woman is prescribed a drug taken in the form of a nasal spray or an injection which suppresses the release of the hormones responsible for the production of an egg. This is necessary in order to establish a 'baseline' from which to start ovarian stimulation and to prevent spontaneous ovulation before egg collection can take place.
• Ovarian stimulation - Once a base line has been established, the woman commences ovarian stimulation which takes the form of a daily intra-muscular injection. Stimulating the ovaries in this way should produce several eggs to ensure that there are enough suitable eggs for fertilization.
• Monitoring - Regular monitoring of the effects of the drugs on the ovaries is undertaken through ultrasound scans and blood tests.
• Final injection - When the ultrasound scan and blood tests indicate that there are a sufficient number of mature follicles (the sacs in which the eggs grow), a final injection is administered to ensure the ripening of the eggs in preparation for the egg collection.
• Egg collection - Eggs are collected from the ovaries through the vagina using a fine needle under ultrasound guidance to aspirate the eggs from the follicles. This is performed as a day-case in our Day Care Unit, typically under sedation.
• Sperm production and preparation - On the day of the egg collection, the male partner is required to produce a semen sample at the centre. The sample is then prepared in the laboratory to extract the most motile sperm.
• Embryology - When all the eggs have been collected, they are put in a dish with the prepared sperm and incubated in the laboratory. Approximately sixteen hours later, the embryologist will check to see whether fertilization has occurred.
• Embryo transfer - If fertilisation has occurred, one or two embryos may be transferred directly into the uterus two days after the egg collection or at the blastocyst stage (see below). The embryos are transfered through the vagina and cervix using a fine catheter. This procedure is usually pain free.
• Pregnancy test - A pregnancy test should be carried out fourteen days after embryo transfer. If the result is positive, an ultrasound scan is recommended two or three weeks later to check the embryo is developing and is correctly situated in the uterus.

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Blastocyst Transfer

A blastocyst is a highly developed embryo that has divided many times into a large number of cells. An embryo reaches this advanced stage of development on day 5 or 6 following insemination.

Bridge offers blastocyst culture and transfer to patients undergoing IVF subject to a number of essential conditions being met. This technique enables us to maintain, or even increase, our IVF success rates whilst significantly decreasing the risk of multiple pregnancy (twins or triplets).

The Timing of Embryo Transfer

During IVF the embryo transfer is usually carried out on day 2 or 3 following theegg collection. At this time the embryos are at the 2-8 cell stage of development. It is very difficult for embryologists to select accurately whichembryos have the best chance of forming a pregnancy at such an early stage of their development but they are all carefully checked using a well-established grading system and the best one or two are transferred in the hope that at least one will implant and result in a live birth.

Sometimes both embryos will form ongoing pregnancies and the result is a multiple (twin or triplet) pregnancy. Multiple pregnancies are associated with an increased risk of complications, such as pre-term delivery, as well as long-term financial implications. It is preferable therefore to transfer only one very good embryo so that those patients who become pregnant only have a single baby, except in the rare occasions when a single embryo cleaves and twins result.

What are the advantages of blastocyst transfer?

Whilst the majority of fertilised eggs will develop into 4-cell embryos, only about half of these embryos will develop to the important blastocyst stage. Therefore, blastocysts are a more “select” group of embryos with a higher chance of implantation. Because they are more likely to form a pregnancy, single embryo transfer can be undertaken without reducing the chance of pregnancy.

Which patients will benefit from blastocyst transfer?

Deciding which patients will benefit from blastocyst transfer is a rapidly developing area. Bridge offers blastocyst transfer to those patients who we predict will develop a large number of embryos and who would have a high risk of a multiple pregnancy if more than one embryo was transferred.

Also, we will recommend it to older patients (age 38 to 44 years) who have a large number of embryos but who have a lower chance of pregnancy because of their age. Blastocyst transfer will allow us better selection of the embryos to transfer.

Blastocysts are transferred in the same way that embryos are transferred.

Your pregnancy test will be due either 11 or 12 days following the Blastocyst Transfer. We will advise you of the date at the time of the transfer.

Freezing and storage of embryos

In cases where more than three embryos result from an IVF treatment, it is sometimes possible to freeze and store these embryos - for five years in the first instance. This enables women to have a further treatment without the need for ovarian stimulation or egg collection.

In order to prepare the uterus to receive embryos, a course of drugs is administered to thicken the endometrium (the lining of the uterus). Embryos are then thawed and replaced directly into the uterus. However, some embryos may deteriorate during the thawing process and would therefore not be replaced.

For Further Information

Call Admissions on 020 7089 1449 and ask for a copy of ‘Bridge Patient Information – Blastocyst Transfer’.

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