The IVF process
An IVF treatment often starts with the use of hormones to stimulate the woman to induce the ovaries to produce more mature eggs than usual.The eggs are then retrieved from the ovaries using an oocyte aspiration needle. In addition, the man provides sperm and fertilisation is achieved by sperm and eggs being brought together in medium (nutrient solution) in a culture dish. This is called conventional IVF. An alternative process is to inject sperm into the eggs using a micropipette. This process is known as ICSI and has revolutionised treatment results for male infertility.
The fertilised eggs, which are called embryos, are then cultured in nutrient solutions, known as media, in an incubator which has a controlled environment that mimics the human body in terms of temperature and pH. After culture for 2-6 days, the most optimal embryo or embryos is/are selected and transferred to the uterus using a transfer catheter. Embryos can be assessed by removing them from the incubator and performing a visual inspection on a number of occasions during the culture process or by utilising new time-lapse technology for monitoring embryos.
Any surplus high quality eggs and embryos can then be frozen so that they can be thawed and used on a later occasion if the treatment fails to result in pregnancy or if more children are desired. There are two methods of freezing. One of these, known as slow freezing, is based on the embryos being slowly frozen in a controlled manner, which takes about 2-4 hours. The other method is called vitrification and is based on an extremely rapid cooling of embryos. This method is also used for cryopreservation of unfertilised eggs.
In the mid-1980s, the pregnancy rate after IVF treatment was in average approximately 15%, and was accompanied by an excessively high rate of twins and triplets, which involved higher risk for the mother and children. Toward the end of the 1990s, the corresponding figure was approximately 25-35% and certain clinics can now achieve 50% or higher.
The underlying reasons are refinement of the method and the further development of the composition of the media used. The pregnancy rate largely depends on the group being treated – age, diagnosis and the number of embryos transferred are all crucial for successful treatment results.
With the introduction of time-lapse technology, the field of assisted reproduction takes a leap forward. Time-lapse monitoring systems present a significant step in improving IVF treatment on all levels. Most important, time-lapse culture and evaluation has been clinically proven to increase clinical outcome and reduce pregnancy loss.