IVF Step By Step - Step Three
The third stage of the IVF process involves ‘assisted hatching' of fertilised embryos. These embryos result from the retrieval of your eggs and their subsequent fertilisation by sperm either from your partner or from a sperm donor. The best quality embryos are then selected for insertion or transfer into your uterus.
For a variety reasons, one of which may be your age if you are a slightly older IVF patient, some embryos may have a tougher outer shell than others. Because the embryo needs to ‘hatch' out of this outer shell before it can be transferred to your uterus, your fertility specialist may decide to carry out an ‘assisted hatching' procedure. When the embryos have had time to divide into eight cells, a needle is used to puncture the embryos' outer shell and allow the embryo to hatch. This procedure usually takes place approximately three days after egg retrieval and fertilisation.
Ready For Transfer?
Embryos are generally considered ready for transfer when they have divided into eight cells and they appear not to have any abnormalities. At this stage, it is possible to carry out chromosome analysis or testing for genetic defects on the embryos, if you so wish. You should discuss this option with your fertility specialist. Some fertility clinics may wait until five days after fertilisation before transferring the embryos. This allows the embryos to reach the blastocyst stage. Blastocysts have a better chance of implantation (becoming secured to the uterine lining as required for pregnancy) than eight-cell embryos, but the risk of multiple pregnancy is higher.
Embryo Transfer Procedure
Where? - Embryo transfer is carried out at your fertility clinic. The procedure is quite similar to a smear test and may be a little uncomfortable. Although many women report that the procedure is painless, you may, under certain circumstances, be given a sedative to help you relax. You should discuss this option with your fertility doctor.
How? - Techniques for embryo transfer vary from clinic to clinic, what follows is a rough guideline as to what you can expect.
You'll probably be asked to undress from the waist down or to put on a special gown. Then you'll sit in a gynaecological exam chair with your feet in stirrups. A vaginal speculum is used to open up your vagina and provide access to your cervix. A saline solution is then used to clean the area around the cervix. Afterwards, a soft, thin catheter is inserted into your uterus and the embryos are transferred via this thin tube into your body. The doctor carrying out the procedure may use an ultrasound device to help him guide the embryos into the correct position. Embryos are usually deposited one to two centimetres from the top of the uterus.
Afterwards - when the procedure is complete you'll probably be told to stay and rest a while at the clinic and to take it easy for the next 24 hours. You fertility doctor may have some advice for you about your activities following the procedure.
How Many Embryos?
In the UK, according to the Human Fertilisation and Embryology Act, a maximum of two embryos can be transferred to the uterus in any one IVF cycle. This is to reduce the risk of a multiple pregnancy, which is more complicated and riskier for both the mother and her babies than a normal pregnancy. In other countries, laws regarding the number of embryos which can be transferred are less stringent, which has resulted in an increase in ‘IVF tourism' among British couples.
If you are lucky enough to have more than two good quality embryos resulting from the fertilisation procedure, you may want to freeze the spare embryos for future use. Talk to your fertility doctor about this option.