First of all, we have to think about the embryo. We know that a chromosomally healthy embryo will have a higher implantation rate, so maybe in that kind of patient, we will have an embryo that does not implant because of this. Indeed, egg donation patients won’t have a very high number of embryos with those kinds of problems but if we transfer an embryo that is not chromosomally healthy, the embryo is not going to implant. So, we can analyse the embryo to make sure that the embryo is healthy in that way.
Apart from that, the patient must be in the best possible condition. We can apply some tests, like the Clotinab immunological test, to check if the patient is healthy in that way. If we find a problem, we have the chance of introducing some treatment to avoid problems with implantation failure. Regarding the uterus, the place where we will put the embryo, it’s very important to have it in the best condition possible. We can analyse the uterus with ultrasound, and if we find a problem such as a polyp or a fibroid, we can remove it so that it won’t have any negative effect.
In recent years, ER activity tests have been applied to make sure that the egg is implanted at the best moment of the patient’s cycle. We know that some patients can have the window of implantation—that is, the moment when the embryo will be implanted—in a higher percentage. A small group of patients might have a window of implantation not in the must-come moment. So, we can do a test like this, and if it turns out that the endometrium isn’t receptive, we can make the transfer at the right moment for the patient.
The reasons for implantation problems in egg donation can be related to the embryos and the quality of the eggs themselves or the chromosomes—for example, abnormalities of the embryos, which can be usually related to the sperm or sometimes to the egg if the selection of the donor was not appropriate. It can be related to the environment of the womb, the uterus, or immunological reasons, and in the end, it can also be because of infection. We have discovered, there is no 100% accurate test that can really indicate chlamydia, ureaplasma, or mycoplasma. So, sometimes the uterus environment inside the lining of the womb can be infected by several factors that can affect the chances of success of a transfer. In cases of recurrent implantation failure with egg donation, we usually advise a treatment course with antibiotics a long time before the embryo transfer. We have found that if we treat such indications with 20 days of antibiotics beforehand, we see some improvement because often endometritis—infection of the womb lining—can play an important role. Sometimes the implantation window can be moved.
We have discovered that the best time to transfer an embryo is on day 5, on some occasions—for example, if we do an ERA test, which is used to determine the implantation window—at this time, the endometrium could be pre-receptive or post-receptive. This is a very good test that tells us whether next time, we should make the transfer a little earlier or later after more or fewer days of progesterone pretreatment. Finally, we need to look at the lining of the womb. On many occasions, we have found problems within the womb lining like polyps, diaphragms, adhesions. A hysteroscopy is required to identify the reason and prescribe treatment, and this can affect the chances of an egg donation cycle succeeding. Hydrosalpinx can sometimes be hidden. For example, we can only find them if we do HSG (hysterosalpingogram). On occasions like this, a laparoscopy or removal of the salpinx does play a role.
The immunological factors can be related to many other issues and intralipid or steroid treatment, or other procedures depending on the specific case, can increase the chances of success. Even the herpes virus has been found to have a negative impact. In cases of recurrent failures, we sometimes give a herpes pretreatment before we do the transfer, and we have found improvement on this as well.
Finally, there occasions when the lining of the womb does not grow. We know that we have not found any reason for this, but the womb lining does not exceed 7 mm. The GCSF, which is a growth factor, a medication that can increase the blood flow in the endometrium has been used on occasions like this, and we do have better results. In general, it needs thorough testing for all the factors, and we need to make sure that none of these issues is present before we go ahead with other options.
