Implantation failure

What is implantation failure?

Implantation is a very complex process. First of all, the embryo must continue development to the blastocyst stage and then break out of its shell. The hatched blastocyst must then implant into the endometrium of the uterus in a short period of time, referred to as the implantation window. For successful implantation of the blastocyst, immune mechanisms are very important that ensure the dialogue between the tissues of the mother and the embryo, which are genetically and immunologically different. Activated cells of the decidual tissue and trophoblast cells produce a large amount of immunologically active substances that cause the necessary immune responses.

Reasons of implantation failure

A process of implantation regulation and occurrence has not been fully discovered. However, it should be noted that in an absolutely healthy married couple with natural conception, the probability of conceiving a child in each menstrual cycle ranges within 20%. Responsibility for such low efficiency is taken both by the embryo itself and by disorders in the interaction between the embryo and the endometrium. Today it is known that one of the main reasons for unsuccessful implantation is the genetic pathology of the embryo.

When analyzing unsuccessful attempts in ART programs, two factors play the most important role: the quality of the embryo (the so-called embryonic factor) and the state of the uterine cavity and endometrium. More rare causes of failure are inflammatory diseases of the pelvic organs, hemostasiological disorders in the coagulation-anticoagulation system, changes in the woman's immune system, endocrine disorders.

Embryonic factor

The quality of the embryo is primarily affected by the quality of the oocytes and spermatozoids obtained for fertilization. Poor quality eggs can be due to the age characteristics of a woman, genetically hereditary factors, endocrine disorders, hormonal diseases of a woman (such as endometriosis), inflammatory processes of the pelvic organs, hormonal stimulation with low-quality drugs.

In case of repeated receiving of oocytes unsuitable for fertilization, and improper embryos for transfer or repeated failures of ART programs, the possibility of switching to oocyte donation programs is considered.

If seminal fluid pathology takes place, it is recommended to conduct additional sperm tests, for example, a test for DNA fragmentation of spermatozoids, and also use ICSI, IMSI, PICSI technologies for fertilization.

In case of repeated implantation failures, it is mandatory for a couple to undergo an embryoscopy during the embryological stage (for maximum visual assessment of the embryo) or pre-implantation genetic testing of embryos to select chromosomally suitable embryos for subsequent transfers.

Types of male infertility

The main reasons for implantation failures on the part of the uterine cavity can be:

• Disorders in the structure of the uterus, the presence of polyps, synechia (adhesions) of the uterine cavity, submucous location of nodes that deform the cavity.

  To determine such conditions, a detailed pelvic ultrasound scan, magnetic resonance imaging of the pelvic organs, hysteroscopy, followed by pathohistological and immunohistochemical examination of the biopsy material are used.

• Chronic endometritis

  (an inflammatory process of the endometrium or an attack by its own cells of the immune system of endometrial cells).
  To exclude this factor, diagnostic hysteroscopy is performed, which gives the opportunity to visualize the endometrium, see its structure, and collect a sample to perform a test for CD 138, CD 56 cells. In case of confirmation of these disorders, mandatory drug treatment is carried out, followed by control with the help of an endometrial pipelle biopsy.

• Immunological factor of implantation disorder

  – in such cases, the own cells of the immune system can attack the embryo or the inner surface of the vessel wall that feeds the embryo at the stage of implantation. At high risk may be women with autoimmune disorders (for example, autoimmune thyroiditis).

• Displacement of the “implantation window”