In the last years, much progress has been made in the development of analytical and ultrasound markers to evaluate the ovarian reserve and therefore be able to predict more accurately the ovarian response and design specific protocols that improve the efficacy and safety of IVF treatments.
However, our knowledge about ovarian physiology is still unsatisfactory. We need to find new markers of follicular development that give us information about oocyte quality and open a path for research to improve it in the future. The first paper is going to tell us about the development of these new markers that participate in the processes of follicular maturation. It opens a very interesting path for the future.
In the second paper the concept of "ovarian sensitivity" will be developed, trying to reveal the reasons why women, with the same reserve, have different responses to ovarian stimulation. At the same time we will debate/discuss if that better response is related to the oocyte quality and therefore to the results both in the laboratory and in the clinic.
It is necessary to move forward in the knowledge of the ovarian physiology, not only in ovarian reserve terms, but also in oocyte quality in order to improve the prognosis of our patients.
What’s an ideal stimulation?
Ovarian stimulation (OS) constitutes an integral part of assisted reproductive techniques. Albeit the first successful in-vitro fertilization (IVF) attempt was conducted in a spontaneous menstrual cycle, soon thereafter OS was introduced to induce development of multiple dominant follicles, and to mature more oocytes to improve chances for conception. Clomiphene citrate, human menopausal gonadotropins and exogenous gonadotropins emerged as the "armamentarium" of drugs inducing OS.
Over the last 30 years, they have become the mainstay in fertility treatment worldwide. In this session of the third edition of Meeting the Experts, two prominent specialists in the field will provide insights on the different options for OS in IVF/ICSI in the search for that "perfect" protocol that will give us an optimal ovarian response, adequate number of oocytes resulting into competent embryos providing good live birth rates and also taking into account safety and patient compliance.
It has always been important and a fundamental part of the doctor's role to take each patient's individual characteristics into account in medical interventions, to obtain the best results and minimise undesired effects. What is more, our profession is increasingly evolving towards personalised medicine. So, for example, in recent decades we have seen how we have adjusted anti-tumour therapies to the genetic and molecular make-up of our patients' tumours, and with the unstoppable advance of knowledge about genetics, in the next few years, we will be looking at designing specific and tailor-made treatments in many fields of medicine.
Reproductive medicine is no exception to this trend and individualised treatment is becoming an increasingly essential part of its success. However, so far, the methods available for personalising treatments are limited. This is why it is important to share knowledge and continue research work on developing new tools that enable us to offer our patients the best options. In this session, the current state of the subject will be described and there will be a discussion on future possibilities.
Conventionally, most IVF embryos are transferred in a fresh cycle. Any surplus embryos available were frozen and stored for later use if no pregnancy results from the fresh embryo-transfer or when patients wish to expand their family. The first live birth after transfer of a thawed cryopreserved embryo was reported back in the early '80s. Nonetheless, the use of frozen–thawed IVF embryos has consistently lagged behind fresh embryo transfer.
More recently, improvements in vitrification protocols have allowed elective freezing of all embryos, followed by transfer in a subsequent cycle (eFET), also known as the ‘freeze-all’ strategy. Initially, this strategy was indicated for hyper-responders, as these individuals are at a high risk of developing ovarian hyperstimulation syndrome (OHSS). Later, it was hypothesized that controlled ovarian stimulation could lead to negative effects in the endometrium and implantation. Hence, it was suggested that performing eFET would not only decrease the risk of OHSS, but also improve the reproductive outcomes in IVF cycles. In contrast, eFET may increase the cost of treatment and workload, requiring additional embryo manipulation and an increase in the time to live birth. In this session of the Meeting the Experts, Prof. Ben Willem Mol will appraise and consider the implications of adopting such a strategy in routine clinical practice.
For the "freeze-all" strategy a bolus of a gonadotrophin-releasing hormone (GnRH) agonist is usually employed as trigger agent. This approach was possible due to the introduction of the GnRH antagonist protocols for the prevention of a premature LH surge, as the GnRH agonist will displace the GnRH antagonist from the GnRH receptor and induce a flare-up of both endogenous LH and FSH, resembling the natural midcycle surge of gonadotrophins for final follicular maturation. Although the surge of gonadotrophins elicited by a bolus of GnRH agonist differs from the natural midcycle of gonadotrophins in duration and profile, it has previously been shown to effectively stimulate final oocyte maturation and ovulation. In the first part of the session Dr. Juan Carlos Castillo will expand on the potential benefits of the GnRH agonist as a trigger agent beyond OHSS prevention.
Embryo implantation is a process that has not yet been made clear. Having a receptive endometrium for a competent embryo is an essential element for this implantation. The receptivity of the endometrium is a situation that to this day still generates debates over what it involves and what it refers to. We are very clear that progesterone is crucial in nature to produce a pregnancy. Its effects on the uterus and the endometrium have not been studied in depth, although uterine contractibility has been established as a direct response to the progesterone.
At present, progesterone and its effects on the endometrium are being postulated as the factor that will tip the scales towards a successful treatment. The importance of the quantity of progesterone levels or the duration of the same, or even if it is necessary or not in certain occasions, opens the debate that will be clarified by our speaker Professor Humaidan.
In the clinical practice, the ultrasound is part of our daily routine. Technological advances are emerging and new ultrasound markers are available for a better non invasive evaluation of endometrial receptivity. For this reason, being able to establish markers like the uterine contractibility marker, among others, would be of great value. Professor Jayaprakasan will clarify these concepts and whether or not they can become useful.
Up until a few years ago, endometrial receptivity could only be assessed using an ultrasound and histological approach. However, in recent decades other ways of ascertaining if an endometrium is receptive are being explored.
In this session, endometrial receptivity factors are assessed using a molecular approach. Dr. Bernabeu will begin by describing the relationship between the microbiome and fertility problems. Evidence has recently shown that there is an endometrial microbiota formed by different micro-organisms that could affect embryo implantation. However, there is no agreement on which species may affect endometrial reception and how. In our group we are pursuing a line of research to identify the species that negatively affect implantation and may, therefore, be the cause of pathologies such as implantation failure or recurrent miscarriage.
It has also been shown that women with implantation failure and recurrent miscarriage present disorders in the expression of endometrial receptivity markers during the implantation window. Dr. Horcajadas has extensive experience in the molecular markers (transcriptomes) that characterise the receptive and refractory endometrium and that define the process of embryo implantation at the molecular level. Currently he is involved in designing new and more accurate test for evaluating endometrial receptivity.
The results presented broaden endometrial receptivity assessment, not only from a morphological perspective but also at the molecular and microbiological levels.
In this session, we will discuss one of the most important markers in assisted reproduction today, such as the "time to pregnancy". Our Medical Director, Dr Rafael Bernabeu will explain that currently, clinicians are coping with more and more demanding patients, strong competence between clinics, arrival of miraculous technology, confounding papers, poor evidences in many of them and the pressure of financial investors making very stressful and difficult designing the optimum approach.
From the point of view of the Gynecologist, our Medical Director, Dr. Rafael Bernabeu will explain the different approaches, which will allow us to obtain an appropriate number of competent gametes, and an optimal endometrium, both essential for the achievement of a pregnancy.
In addition, Dr. Bernabeu will discuss the different strategies, such as the accumulation of oocytes and/or embryos, which may be valid for certain reproductive disorders, such as low ovarian reserve. From the point of view of the Embryologist, Dr. Etienne Van den Abbeel will focus on new methods of selection and embryo culture, which will allow selecting the best embryo for transfer, with more possibilities of obtaining a single and ongoing pregnancy and subsequent birth of a healthy child.
In this session on preimplantation genetic testing (PGT-A) we will be discussing two topics that will highlight the main debates and controversies in this field.
Embryo aneuploidy is one of the leading causes of failure in IVF cycles. Although selecting euploid embryos by means of PGT-A (Preimplantation Genetic Testing for Aneuploidy) has been put forward to improve success rates in IVF cycles, recent studies have questioned the benefits. In response to these criticisms, other authors recommend limiting PGT-A to certain cases, such as recurrent miscarriage and advanced maternal age. The issue is open to debate.
To carry out PGT-A, an embryo biopsy in D+3 or D+5 is required, which may reduce its ability to implant. New methods have been developed that propose using the embryo culture medium as a source of DNA. Such an alternative would avoid embryo biopsy but this new methodology has yet to confirm its diagnostic ability.
Recent studies suggests that oocyte mitochondrial content and function may be related to implantation success and embryo viability. Our research group, led by the Scientific Director, Dra. Belén Lledó, has recently published an article addressing the importance of mitochondria in reproduction. In this context, Dra. Lledó will comment on our own results obtained at Instituto Bernabeu, which will deal not only with the number of copies of mitochondrial DNA, but also with the functional capacity of the mitochondria and its role in reproduction.
The embryologist is the one ultimately responsible for the success of the IVF laboratory. Therefore, an optimal embryo selection is essential to improve clinical outcomes in an assisted reproduction program. In this line, complex mathematics models and algorithms are now being developing, checking and validating in order to select the best embryo for transfer and to help embryologist in this responsible and at the same time subjective task. In this final presentation, Dr. Diego Ezcurra will explain the latest advances in this promising area of artificial intelligence.