Implantation Failures: Causes and Solutions for Embryo Implantation
What causes implantation failure? What tests should I undergo? In the following, Dr. Héctor Izquierdo tells us how embryonic implantation develops and what conditions are favorable for the embryo to implant in the endometrium.
Additionally, we will examine the most effective fertility treatments that can improve the chances of successful implantation, providing hope and opportunities for those seeking to start a family.
When does embryo implantation occur?
The phase of embryo implantation encompasses the process by which an embryo establishes a connection with the endometrium, marking the beginning of pregnancy. From this point, the embryo will unfold its development and that of the structures that contribute to its nourishment, including the yolk sac and placenta.
With the activation of the beta-hCG hormone at this moment, which in turn triggers the first signs of pregnancy in the woman, a process unfolds that also depends on the state and characteristics of the uterine endometrium, where the appropriate thickness and appearance must exist to facilitate successful implantation and the subsequent progress of gestation.
How long does embryo implantation take?
When fertilization occurs in the laboratory through IVF or ICSI, embryos are placed in incubators that maintain conditions similar to those of the human body. It is at the blastocyst stage where the embryologist selects the most viable embryo for transfer to the maternal uterus, thus facilitating implantation.
Embryonic implantation occurs during the period spanning from the seventh to the tenth day after fertilization, resulting in the rupture of some blood vessels and capillaries in the endometrium, which is thickened and highly irrigated to accommodate the embryo.
This stage of the process, known as the adhesion phase, is crucial as it marks the beginning of pregnancy. At this point, approximately 30% of women experience what is known as implantation bleeding.
Thanks to this correct adhesion of the embryo to the inner walls of the endometrium, the future baby will begin to obtain nutrients from what will later become the placenta, which is not yet fully formed.
Favorable conditions for embryo implantation
For embryonic implantation to occur, the embryo and endometrium must have the right conditions.
However, what happens if the embryo does not implant properly? Not all women achieve pregnancy on the first attempt; many women end up with ectopic pregnancies… we are talking about implantation failures.
Implantation Failure: What are they and what causes them
In the context of assisted reproduction, we can refer to implantation failure when a patient does not achieve pregnancy after completing 3 cycles of IVF using her own eggs or after 2 cycles of egg donation. This applies in situations where:
- High-quality embryos have been transferred.
- No technical issues have arisen during embryo transfers.
- No obvious problems exist in the uterus.
Causes of embryo implantation failure
Various conditions can lead to implantation failure and may be linked to embryonic factors, uterine problems, or even immune disorders that affect reproductive health
Below, each of the possible causes of implantation failures is described.
Among the causes that can lead to embryonic implantation failure are genetic alterations in the embryo, namely, the egg or sperm. Additionally, some embryos may have disorders in the zona pellucida, which hinders their ability to hatch and separate in the implantation process.
The zona pellucida (ZP) is an outer layer composed of glycoproteins that covers the egg and embryo after fertilization.
Certain elements reduce the receptivity of the endometrium, including:
- Asymptomatic chronic endometrial infections.
- Endocavitary anomalies such as polyps, septa, or adhesions.
- Displacement and irregularities in the implantation window, such as its advancement or postponement relative to 6-7 days after fertilization.
Some of these alterations can be addressed with medication or procedures such as hysteroscopy.
At times, problems stem from alterations in systems unrelated to reproduction. In such cases, the importance of tailored treatment should be emphasized.
- Thrombophilias: These involve alterations in coagulation processes. While they contribute to implantation failure, coagulation issues can also lead to repeated miscarriages.
- Immune system disorders: The embryo may be rejected as foreign due to conditions like antiphospholipid syndrome. This rejection hinders embryo implantation in the woman’s uterus.
While the mechanism by which these causes affect embryonic implantation remains unclear, ongoing research is focused on new diagnostic tests to properly apply treatment.
Solutions for implantation failure in assisted reproduction laboratories
Cases of implantation failures increase with maternal age. Nevertheless, specific tests aid our professionals in making accurate diagnoses.
Preimplantation Genetic Testing or PGT
The incidence of implantation difficulties is more pronounced in older women due to an increase in chromosomal abnormalities in eggs. Currently, it’s possible to select healthy embryos in the lab using Preimplantation Genetic Testing (PGT), also known as Preimplantation Genetic Diagnosis (PGD).
This complementary technique assesses the embryo’s genetic profile through a biopsy without affecting its development.
>> For a more detailed understanding of PGT, you can continue reading here <<
Treatment with heparin
For women with thrombophilia, heparin may be recommended as a treatment. This is administered from before pregnancy until childbirth. Heparin is a natural anticoagulant found in the body’s tissues.
Endometrial Receptivity Test (ERA)
The Endometrial Receptivity Array (ERA) is a molecular diagnostic approach that analyzes the expression of a set of genes linked to the state of the endometrium. This provides information about endometrial receptivity at the time of biopsy.
Following the biopsy, the genetic profile of endometrial receptivity is examined at the moment of sample collection. Based on the results, it’s evaluated if the implantation window is displaced. Therefore, if the endometrium is receptive, it’s the ideal time for embryo transfer.
Assisted hatching involves creating a small opening in the zona pellucida of the embryo to facilitate its release during expansion.
This is beneficial for promoting implantation in embryos with thickened or elongated zona pellucida (the ZP elongates, giving the embryo a flattened appearance).
Extended cultivation to blastocyst
In an in vitro fertilization process, specialists observe embryo development in the lab using time-lapse technology. It’s possible to track development until the embryo reaches the blastocyst stage (day 5) or to detect if development halts at an earlier stage.
Extending cultivation to the blastocyst stage allows for more precise embryo selection, and transferring on day 5 ensures better synchronization between the embryo and the endometrium.
What is the most effective treatment for successful embryo implantation?
The ideal treatment is the one that results in the generation of high-quality embryos. Our specialists recommend egg donation when pregnancy is not achieved due to implantation failures.
Egg donation becomes a viable solution in cases of repeated implantation failure, where embryos are transferred to a uterus and endometrium in good condition. An increase in implantation rates has been observed in these cases, where egg donation allows for the acquisition of superior-quality embryos.
According to our Dr. Héctor Izquierdo, “Regarding success rates, we can first divide them by the origin of the embryo, whether it’s IVF with one’s own eggs or egg donation. In IVF with one’s own eggs and euploid embryos, we are close to an 80 percent pregnancy rate and a 60 percent live birth rate. In the case of egg donation, the cumulative live birth rate after 3 embryo transfers is around 90%.”
Hence, IVF with donor eggs presents high success rates. However, it’s essential to consider the particularities of the recipient’s endometrium at the time of embryo transfer.
In the case of a diagnosis of severe male factor infertility, this can also impact embryo implantation. For this reason, in such situations, it’s advisable to consider IVF with both sperm and egg donation, what we refer to as “double-donation.”
Why choose Vida Fertility Institute?
At Vida Fertility Institute, we understand the complexity you may be experiencing. Implantation failure can generate uncertainty and frustration, but we also want to remind you that you’re not alone on this journey.
Our team of experts in assisted reproduction is here to provide you with the support and personalized attention you need.