Implantation failure is one of the most current issues in assisted reproduction units and researchers: why, when embryos are implanted from In Vitro Fertilization or Without Sperm Microinjection (IVF/ICSI), of good quality and in patients with ultrasonographically normal uterus and endometrium, they do not implant and the desired pregnancy does not develop?
Causes of embryo implantation failure
There are many factors related to such implantation failure. It may be due to:
- Embryonic alterations: although morphologically and dynamically normal, they may present genetic alterations or alterations in their division machinery, which prevents their progression or implantation.
- Immunological factors: they represent the interaction of the embryo and the mother. This immunological interaction is intertwined with various endocrine, paracrine, coagulation system and inflammatory factors.
- Hormonal or endometrial alterations: it is important that the implantation window, which is the period of time in which the endometrium (uterine tissue where embryo implantation will take place) is receptive, occurs at the expected time, which may not happen due to these hormonal or local endometrial alterations. One of the most frequent is chronic endometritis (CE).
Chronic endometritis: what it is
Chronic endometritis (chronic inflammation of the endometrial layer of the uterus) is a usually asymptomatic disease, caused by the colonization of the endometrium by germs or mycoplasmas. This pathology has no ultrasound translation and its diagnosis is based on findings:
- Hysteroscopic, by visual exploration of the endometrial cavity with an optical system. What is observed are micropolyps.
- Anatomopathologic, based on a microscopic study of an endometrial biopsy. What is found is an abundance of plasma cells.
- Microbiological culture of a tissue sample to check for bacterial and/or mycoplasma growth.
How to diagnose chronic endometritis in IVF treatments and relationship (or not) with implantation failure.
Since hysteroscopy, biopsy and endometrial cultures are not part of the basic study prior to an IVF cycle, the frequency of chronic endometritis in the infertile population is unknown. In the infertile subpopulation with implantation failure, there are studies that find varying rates of CD ranging from 15%, 30% or 60%.
However, there is no agreement as to the relationship between chronic endometritis and implantation failure. While Kasius is of the opinion that chronic endometritis does not negatively affect the results in terms of pregnancy and birth rate after IVF/ICSI, Cicinelli finds an improvement in the results after antibiotic and hysteroscopic verification. Thus, the gestation rate with treated patients is 65% compared to 33% in patients in whom CD data persisted. Likewise, the live birth rate is 60% versus 13% in patients with CD. Similarly, Johnston-MacAnanny also finds a high rate of endometritis in IVF/ICSI patients with Implantation Failure.
Recommendations and treatment of chronic endometritis
Despite the heterogeneity of opinions and such discordant findings, the expert in Assisted Reproduction will recommend, in all cases of implantation failure, to perform the necessary studies to rule out chronic endometritis by hysteroscopy, biopsy and endometrial culture.
If chronic endometritis is present, it will be treated with ten days of antibiotics before proceeding with a new IVF/ICSI attempt.