It is often difficult for patients to understand why, after obtaining eggs and sperm, combining them successfully in the laboratory to develop into embryos and putting these healthy dividing embryos into the uterus, IVF does not possibly succeed. As with most biological events, pregnancy is a very complex process. Even today, what we do not know about pregnancy continues to exceed what we do know. Nevertheless, there are some specific factors that we have identified that can commonly lead to IVF failure.
Some causes of IVF failure
Egg abnormalities
The human egg is a very delicate structure. So, it is subject to damages that can render it nonfunctional. As the egg ages, the delicate contents are prone to breakage – such breakage can result in an abnormal oocyte. The oocyte is also subject to damage due to the presence of free radicals, reactive oxygen species and other products of metabolism that occur within the ovary as a woman ages. Many recent studies have shown that between 25 and 40 per cent of all oocytes are chromosomally abnormal. This number obviously increases as a woman ages.
Abnormal sperm
Although abnormal sperm appear to be a less common factor affecting the success of an IVF cycle, they nevertheless play an important supporting role. Have you ever wondered why sperms are present in their millions? This is because not every sperm can fertilize an egg. Rather, the process of fertilization itself is very complex. In order for sperm to migrate to the egg, they must be able to swim. In other words, the tail of the sperm must be able to propel the sperm through the female reproductive tract to the egg. The sperm eventually penetrates the egg where the nucleus of the sperm opens, releasing the sperm DNA. At that point, the chromosomes from the sperm and the chromosomes from the egg combine, producing a fertilized egg (which is actually a very early embryo). Studies suggest that the incidence of chromosomal abnormalities in sperm is far greater than that seen in eggs. Intracytoplasmic sperm injection (ICSI) was developed to enable men with very low sperm counts, low motility or very few normal sperm to be able to achieve fertilization and pregnancy.
Embryo selection methods
The embryos that are ultimately transferred into the women’s uterus are selected by the embryologist. Unfortunately, our ability to distinguish chromosomally normal from chromosomally abnormal embryos remains severely limited. Essentially, our embryologists select embryos for transfer based on three basic criteria: cell stage, embryo grade and the rate of cell division.
IVF Laboratory factors
The IVF laboratory is a very tightly controlled environment, in which we attempt to simulate what sperm, eggs and embryos experience inside the female reproductive tract. Specifically, we tightly control oxygen concentration, carbon dioxide concentration and other factors such as humidity, PH, temperature and light. Even slight alterations from what embryos normally experience can lead to death of the embryos and therefore no chance for pregnancy from the resulting cycle. Our embryologists continuously keep up with the changing literature and make alterations in our laboratory as necessary, in order to continue to optimize the environment to which gametes and embryos are exposed. In addition, they perform daily quality assessment and control procedures in order to confirm that our equipment is always functioning optimally. The construction of the laboratory itself was meticulously overseen in order to guarantee an optimal laboratory environment.
Problems with egg retrieval and embryo transfer
The surgical procedures themselves, the egg retrieval and the embryo transfer, are very important to the success of an IVF cycle. Retrieving fewer eggs than expected, or even worse failing to retrieve any eggs, can lead to an adverse outcome. In addition, during the embryo transfer procedure, one of the most important steps of the entire cycle is that embryos must be placed in the correct location. In our practice, we transfer embryos under guidance by ultrasound to ensure that they are placed in the best position possible inside the womb. In addition, prior to transferring the embryos, we remove any cervical mucus or other cellular debris that may plug up the transfer catheter. We also pre-treat all of our patients with a smooth muscle relaxant in order to prevent contractions of the uterus.
If the eggs are good, the sperms are good, the embryos are good, the womb is good and the process of transfer was smooth. Then, the last factors to consider are the immune factors. These contribute to about 60 per cent of implantation failure.
Immune factors
The immune system of individuals usually protects them from foreign agents like bacteria, viruses, cancer cells etc. There is evidence now to show that these immune factors recognise an embryo as being foreign and when this happens, it destroys the embryo on sight, making it extremely difficult for such patients to get pregnant. These factors include natural killer cells, embryo toxic factors, blocking factors, platelet leukocyte aggregation, etc. Unfortunately, these tests are quite expensive but after three failed IVF cycles, we recommend these tests to be performed for our clients and from the results, necessary treatments are offered.
Many patients come to Vine Branch Fertility Centre (VBFC) following unsuccessful treatment elsewhere. After reviewing their medical records, we may suggest such things as a different IVF protocol, the use of ICSI, proceeding to donor gametes or immune factor screen. It is important to realise that different IVF centres may approach the same patient in a different manner. Therefore, failure at one facility does not mean that you should give up on your dream of having a baby. At VBFC, dreams do come through.
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