In Vitro Fertilisation (IVF)
The basic principles of IVF are to switch off the natural control mechanism of producing 1 egg per month. This is done by using a combination of natural hormones which are used to stimulates the ovaries to produce eggs. This is a totally natural and administered by a subcutaneous injection, (an injection into the fat using a small fine needle just beneath the skin) and another hormone which is used to promote the human pregnancy hormone.
One unnatural hormone is used which switches off the control mechanism to produce only 1 egg. This can be administered either as a twice daily, or as a daily subcutaneous injection, or a monthly one off small injection as an implant about the size of a match head just beneath the skin.
The switching off usually starts on day 21 of a contraceptive pill cycle (taken from day 1 of the period for 3 weeks) We recommend a contraceptive pill that has the effect of not allowing the ovaries to produce ovarian cysts which can delay an IVF cycle.
The daily injections start after 2 weeks of the switching off medicine, and the ovarian response is monitored by ultrasound scans. These are usually done with a vaginal scan probe with an empty bladder. The aim is to collect between 5 to 25 eggs. Each collection of fluid in the ovary (follicle) has the potential to contain only 1 egg. If there is any question about the quality or number of eggs from the scan then a blood test will be taken to measure the level of the female hormone estrogen.
The late night injection is given when the leading follicle reaches 18 to 20 mm and the lining of the womb (endometrium) is at least 8 mm thick. The lining needs to be thick enough to provide a good quality environment for the fertilised eggs (embryos) to implant. Taking a gardening analogy the aim is to provide simultaneously good quality plants (Embryos) and a receptive environment for the embryos to plant in and provide nutritional support (i.e. good quality soil).
The egg collection is done as an ultrasound technique utilising a vaginal probe with an empty bladder and a fine needle to suck the eggs from the ovaries. It is performed either under general anaesthetic or deep sedation. The sedatives used are very powerful and have the effect of becoming very dopey and combined with a powerful painkiller, an antibiotic (usually a type of Penicillin) and an anti sickness medicine then the woman is usually unaware of the procedure and remains comfortable. On the same day as the eggs are collected the male partner produces a sample of semen.
The best quality sperms are selected and either mixed with the eggs if there are enough good quality ones (IVF) or injected into the eggs (ICSI).
Success rate of IVF
This depends on the age of the woman. If the age is up to 25 then pregnancy rates of 50% are achieved. For ages between 25 to 35 years, then the success rate gradually decreases so that an average of 33% is common. However by the time a woman reaches the age of 44, then the success rate will be less than 4%. Related to age the other most important determinant is the baseline FSH. This is a blood test done in a preceding cycle between days 2 to 6 of the woman’s period. A value of under 10 suggests that the outcome is likely to be successful. However a blood level of over 15 suggests a poorer chance of pregnancy than would be expected taking into account age alone. A level over 50 indicates that the woman is in the menopause, by which time of course the periods will have stopped and no eggs can be collected.
Complications of IVF
IVF is a very safe procedure that has been refined since the birth of Louise Brown in 1978 i.e. nearly 30 years ago. However like most things in life an absolutely perfect outcome with no problems cannot be guaranteed. The problems can include an infection where the needle went into the vaginal skin, which is rare (less than 1%) with the use of routine antibiotics, or bleeding from the needle puncture site which is treated by pressure with a tampon similarly to pressing on the skin when having a blood test.
A rarer problem is OHSS. In this condition the ovaries swell and fluid leaks out intro the abdomen. It is preventable by careful monitoring of the egg growth. In mild cases drinking plenty of water is all that is required. In rare cases hospital admission is required with a drip and a drain through the abdominal skin to drain off the excess fluid.