In Vitro Fertilization
Nowadays it has become the converging point for any reproductive failures which could not be initially solved by a simpler way, through the treatments described previously. Moreover, the IVF, and particularly the Intracytoplasmatic Spermatic Injection (ICSI), is the solution to male sterility, therefore we can state today that male sterility has become a problem of the past in most cases.
The IVF consists in six stages: 1.- Ovarian stimulation with hormones, 2.- Oocyte extraction, 3.- Insemination, 4.-In-vitro culture until embryo in different stages of development, 5.- Embryo transfer6.- Freezing and unfreezing of embryos in some cases.
The ovarian stimulation allows us to obtain several ovules in one single cycle and is necessary since the pregnancies possibilities increase proportionally to the number of embryos transferred, considering that not all the oocytes obtained evolve to embryos suitable for transferring.
The stimulation requires intramuscular and/or subcutaneous injections and several (3 or 4) visits to the IVI Center to monitor their results. The probability that an exaggerated response occurs (hyper stimulation) is less than 1%.
Oocyte extraction: The extraction is carried out through a transvaginal puncture under ultrasound control. The average duration for this intervention is about 15 minutes, it is carried under sedation and the patient will be ready to go home in 20-30 minutes. The risk of suffering some complication during the oocyte extraction is 1 among 2.500 cases, so it can be considered invisible.
Insemination. Once we have obtained the oocytes, a semen specimen is required. In order to carry out the insemination there are two alternatives: the classical insemination, placing the oocytes together with the spermatozoa, previously treated and selected; and the intracytoplasmatic spermatic injection (ICSI), which we are detailing below. By this way, we can practically solve any kind of male sterility.
In Vitro Embryo Culture. The fertilized oocytes are checked in the following day. From this moment on the embryos are kept in an adequate type of culture for its particular development. The embryos usually stay in the culture for three days. In some occasions, it is convenient to extend the culture in the laboratory till the stage called blastocyste. For this purpose we use the Embryo Co-culture Technique with endometrial cells, which has been first developed by the IVI and whose utility has been internationally recognised. Not in vain we have been given American Fertility Society for Reproductive Medicine Annual Award three times (1995, 1997 and 1999) for our works on the development of the embryo co-cultures. In fact, what we do is to culture the embryos together with cells from the human endometrial epithelium, which is their natural environment. In these cultures the embryos are developed for 6 days, most of them reaching the best stage for their implantation.
Embryo transfer: The moment for the embryo transfer into the maternal uterus is decided for each particular case. Depending on the embryo characteristics, embryologists recommend the most suitable moment between he second and the sixth day after the obtaining and fertilisation of the oocytes. Then, the transfer may be carried out either into the uterus or into the tubes. The uterine transfer takes place transcendentally, does not require anaesthesia and is the most common in IVF. We usually transfer 2 or 3 embryos, since the present high rate of embryonic implantation advises to limit their number in order to reduce the incidence of multifoetal (our statistics show that this is the number which produces best pregnancy rates without increasing multiple gestation risk).
Concerning IVF results at the IVI, they are among the highest in the world, what we notice year after year in the different international forums where we share our experiences with other human reproduction specialists. As part of our policy about providing our patients with true information on success rates we have created a section on our website where we inform each year about the previous year results, apart of other interesting novelties. We consider this information to be essential to help couples decide on one center or another.
We can say that since the end of 1999, and in a constant way for the last years, pregnancy rates with IVF and ICSI were never fewer than 50%, being over 60% for oocyte donation. Furthermore, the success rates with frozen embryo transfer are now comparable to the rest of treatments, being over 40%.
Freezing and unfreezing of embryos: after the transfer of the right number of embryos for each case, the rest of feasible embryos are submitted to a freezing process in order to preserve them for a time. This procedure allows the availability of these embryos in case they are needed by the couple. If pregnancy was not achieved, or after finishing it, we proceed to unfreeze and transfer the embryos that survived freezing. Although historically the results have been lower than for the other treatments, at the IVI Centers they have been almost equal to IVF’s for the last two years. There is not a greater risk of miscarriage or embryo malformations when transferring cryopreserved embryos.