In vitro fertilisation (IVF)
‘In vitro fertilisation’ is a procedure that is most commonly used to treat infertility in female patients, usually where infertility is caused by an abnormality of the fallopian tubes or when female patients have already undergone menopause. It can also be used in some cases of male infertility where healthy sperm are present but are too poorer quality to facilitate fertilisation unaided. The term ‘in vitro’ refers to the fact fertilisation occurs outside of the body. If fertilisation is successful the egg is reinserted into the uterus and pregnancy continues as normal.
Treatment cycles usually begin on the third day of menstruation. A combination of fertility drugs is taken daily (via an injection) over a period of 10 days in order to facilitate the growth of multiple follicles within the ovaries. Other drugs may be used to prevent spontaneous ovulation.
When maturation is judged to be complete ‘human chorionic gonadotropin’ is used to stimulate ovulation which in most patients occurs 36 hours after the injection. Just prior to ovulation a transvaginal procedure is performed where a needle is inserted into the ovaries through the wall of the vagina in order to aspirate the follicular fluid from which eggs can be identified. The procedure takes approximately 20 minutes and can be performed using either conscious sedation or general anaesthetic.
After your procedure
Once the follicular fluid has been aspirated the eggs are identified and the surrounding cells removed. Sperm is then prepared and incubated with the selected eggs for about 18 hours until fertilisation has taken place. If sperm quality is an issue an intracytoplasmic sperm injection can be used in which a single healthy sperm is inserted directly into the egg. Successfully fertilised eggs are then graded based on the number of cells, level of fragmentation and degree of growth and the most suitable eggs transferred to the uterus once they have reached the 6 -8 cell stage (typically after 48 hours). Implantation is accomplished using a catheter which is inserted through the vagina into the cervix. It is common for several embryos to be transferred in order to improve the chances of implantation and pregnancy.
Long term outcome
Successful pregnancy occurs in approximately 30% of patients who undergo IVF treatment however these rates are greatly affected by several factors. In cases where a female patient’s own eggs are used as opposed to eggs provided by a donor, pregnancy rates can increase by up to 15%. Age is also a significant factor as in women over the age of 40 pregnancy rates may fall to less than 5%.
IVF may be unsuccessful for several reasons. The timing of ovulation may be misjudged, attempts to retrieve eggs may be unsuccessful and successfully retrieved eggs may be found to be abnormal. The fertilised egg may fail to undergo cell division or the embryo may not successfully implant itself in the uterus once it has been transferred.
The most common complication associated with IVF is the possibility of multiple births as a direct result of transferring multiple embryos to the uterus. The result is the development of twins, or even triplets. Identical twins may result if the egg is split inside the uterus.
As with any surgical procedure there is a risk of human error or infection, however such complications tend to be very rare. A very small number of patients may develop ovarian hyper-stimulation syndrome in which the ovaries become enlarged resulting in nausea, diarrhoea and weight gain. There is very little evidence to suggest that IVF babies are more prone to acquiring birth defects, although if an intracytoplasmic sperm injection is used the risks may be slightly higher.