The hormonal stimulation of the woman can give the decisive impetus for the long-awaited offspring. The body is gently prepared for pregnancy. Ovarian stimulation is aimed at inducing the maturation of multiple that contain the maturing oocytes. This requires a targeted and perfectly timed approach. It is actually comparable to a group of children taking part in a 100-meter-sprint. If they are well- trained and prepared, they will exactly know what to do and will therefore start running at the same time. Without the necessary training, however, they would probably perform in an uncoordinated and chaotic way, and the desired success would fail to materialize.
At the IVF Centers Prof. Zech we mainly use the so-called Long-Protocol for ovarian stimulation. The aim is to obtain the highest possible number of oocytes during follicular puncture for the subsequent fertilization with the partner’s sperm.
Ovarian stimulation leads on average to the maturation of 10-12 follicles resulting – in the ideal case – in the retrieval of 10-12 oocytes. Usually, 80 % of them can be fertilized after IVF / ICSI / IMSI. Thus, it can be assumed that the chances of getting pregnant in an IVF cycle (these chances are , of course depending on the woman’s age and the quality of the sperm), the preparation of which takes about 1.5 months, are similar to those of a fertile couple within one year. This means: Typically, a woman aged 30 ovulates every month – thus producing a total of 12 oocytes per year. However, not every fertilized oocyte is capable of resulting in the development of a healthy child. On average, this applies to only every third oocyte in humans. It might be the oocyte resulting from the ovulations in January, February, September or November, provided, of course, that sexual intercourse takes place at the most effective time. Depending on semen quality, there might also be significantly more or less oocytes that prove capable of developing beyond the blastocyst stage into a healthy child.
The reasons for applying the Long Protocol
At the IVF Centers Prof. Zech we aim at obtaining a number of ova, equal to that produced in the natural way by a healthy woman within one year. Typically, from a number of 10-12 follicles one follicle becomes dominant (= dominant follicle), i.e. each month about 10-12 follicles are “fighting” for dominance. The dominant follicle ensures that the other “rivals” fail to succeed.
We intend to send all available follicles “into the race” at the same time. We do not want to have one dominant follicle but, if possible, all of them should be dominant! These follicles (also known as pre-antral or antral follicles) are on average between 3 and 8mm and are in a dormant state. In a normal cycle, there are, already at the very beginning, one or two follicles in the start position and then they “run off”. In the end, of the two “rivals” there remains only one follicle containing the mature oocyte.
Using the Long Protocol involving the start of down regulation in the second half of the woman’s previous cycle, all available oocytes are “ready to race” at the same time. This is how most of them “manage” to develop into mature oocytes. Prolonged down regulation often allows for the development of additional follicles. This is particularly important in women regarded as so-called “Low Responders”, i.e. women in whom a relatively small number of oocytes is expected to be achieved. Once again: A sufficient number of oocytes may serve as a good basis for fertilization, thus substantially boosting the chances of a healthy pregnancy in every cycle. Furthermore, it offers the opportunity to obtain additional embryos to be cryopreserved for future attempts at IVF in order to give birth to another child!
Short Protocol and Antagonist Protocol
When using a Short Protocol, the struggle for dominance commences at a point in time when a relatively large number of follicles (preantral or antral follicles) are not yet ready to start – they are still just “warming up”. Therefore, this is not the most suitable moment for “kicking off” the process.
In our opinion, the Antagonist Protocol should be applied only in very few exceptional cases, for example when follicular puncture has repeatedly resulted in the retrieval of nothing but immature oocytes. This rarely happens, but if it occurs it is mostly due to the fact that the woman does not respond to the hormone HCG which is administered to trigger final oocyte maturation. In these cases we recommend that the patients undergo a cryo cycle in the first place, since the Antagonist Protocol may have a negative impact on the uterine lining (and may also results in oocytes of poorer quality). It is like a defibrillator: it should only be used in cases where the heart has already stopped beating and not while the heart is beating!
A Short Protocol is indicated only in a few rare cases and should be used on a strictly individual basis. Indications for the Short Protocol are even rarer than those for the Antagonist Protocol!
Low risk for ovarian hyperstimulation syndrome
When experienced specialists in reproductive medicine carry out ovarian stimulation by using the Long Protocol while also considering the possibility of a primary cryo cycle (depending on the situation we prefer the vitrification of blastocysts), the risk for ovarian hyperstimulation syndrome is very low.
In case of a cryo cycle, the medication is stopped after egg retrieval and the obtained embryos are frozen. The ovaries are “calming down” within 3-5 days and, in the majority of cases, the onset of ovarian hyerstimulation syndrome can therefore be prevented. A primary cryo cycle seems to be useful in promoting embryo/blastocyst implantation on day 5, since these embryos are transferred to a “more natural” mucous membrane.
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