Fertility Topics Explained from the Experts at SFS
“IVF is neither a pure art or a pure science. Rather it is a blend of both!” “Virtually nothing that we do clinically in IVF can be fully supported or validated by “gold standard statistical analysis. This is because in the ART setting, when it comes to establishing comparative evidence of clinical efficacy, randomized controlled statistical assessments cannot be applied. Such determinations of outcome would require stabilizing all variables involved so as to assess the effect of varying one or two. Accordingly, quality IVF medical treatment is a function of the application of valid scientific principles against the back-drop of experience and seasoning.” GS The most important application of the IVF art-science blend concept is best appreciated when applied to the selection and implementation of protocols for controlled ovarian stimulation (COS): The importance of the IVF stimulation protocol on egg/embryo quality cannot be overstated. This factor seems often to be overlooked or discounted by t IVF practitioners who use a “one-size-fits-all” approach to ovarian stimulation. My experience is that the use of individualized/customized COS protocols can greatly improve IVF outcome. While no one can influence underlying genetics or turn back the clock on a woman’s age, any competent IVF specialist should be able to tailor the protocol for COS to meet the individual needs of the patient. Gonadotropins (LH and FSH), whether produced by the pituitary gland or administered by way of fertility drugs, have different “targeted” sites of action in the ovary. FSH targets cells that line the inner wall of the follicle (granulosa cells) and also form the cumulus cells that bind the egg to the inner surface of the follicle. Granulosa cells are responsible for estrogen production. LH, on the other hand, targets the ovarian connective tissue (stroma/theca) that surrounds ovarian follicles resulting in the production of male hormones such as testosterone (predominantly), androstenedione and DHEA. These androgens are then transported to the granulosa cells of the adjacent follicles in a “bucket brigade fashion”. There FSH converts testosterone to estradiol, causing granulosa cells to multiply (proliferate) and produce estradiol, follicles to grows and eggs to develop (ovogenesis) It follows that ovarian androgens (mainly testosterone) is absolutely indispensable to follicle/ egg growth and development. However, the emphasis is on a “small” amount of testosterone. Over-exposure of the follicle to testosterone can compromise egg development and lead to an increased likelihood of chromosomal irregularities (aneuploid) following LH/hCG-induced egg maturational division (meiosis) and compromise embryo “competency/quality. Ovarian androgens can also reach the uterine lining where they sometimes will compromise estrogen receptor -induced endometrial growth and development. Many older women and those who have diminished ovarian reserve (DOR) have increased LH activity is increased. Such women either over-produce LH and/or the LH produced is far more biologically active. Chronically increased LH activity leads to overgrowth of ovarian connective tissue (stroma/theca). This condition, which is often referred to as Stromal Hyperplasia or hyperthecosis can result in excessive ovarian androgen/testosterone production and poorer egg-embryo quality/competency, Similarly, women with polycystic ovarian syndrome (PCOS), also characteristically have Stromal hyperplasia/hyperthecosis due to chronically increased LH activity. Thus they too often manifest with increased ovarian androgen production. It is therefore not surprising that “poor egg/embryo quality” is often also a feature of PCOS. In my opinion, the over-administration of LH-containing menotropins such as Menopur, [which is comprised of roughly equal amount of FSH and hCG ,which acts similar to LH)], to older women, women with DOR and those who have PCOS can also lead to reduced egg/embryo competency . Similarly, drugs such as clomiphene or Letrozole that cause the pituitary gland to release excessive amounts of LH, are also potentially harmful to egg development and in my opinion, are best omitted from IVF COS protocols. This is especially the case when it comes to older women and those with DOR, who in my opinion should preferably be stimulated using FSH-dominant products such as Follistim, Puregon, Fostimon and Gonal-F. Gonadotropin releasing hormone agonists (GnRHa): GnRHa such as Lupron, Buserelin, Superfact, Gonopeptyl etc. are often used to launch ovarian stimulation cycles. They act by causing an initial outpouring followed by a depletion of pituitary gonadotropins. This results in LH levels falling to low concentrations, within 4-7 days, thereby establishing a relatively “LH-free environment”. When GnRHa are administered for about 7 days prior to initiating gonadotropin stimulation (“long” pituitary down-regulation”), the LH depletion that will exist when COS is initiated, will usually be protective of subsequent egg development. In contrast, when the GnRHa administration commences along with the initiation of gonadotropin therapy, there will be a resultant immediate surge in the release of pituitary LH with the potential to increase ovarian testosterone to egg-compromising levels , from the outset of COS. This, in my opinion could be particularly harmful when undertaken in older women and those who have DOR. GnRH-antagonists such as Ganirelix, Cetrotide and Orgalutron, on the other hand, act very rapidly (within hours) to block pituitary LH release. The purpose in using GnRH antagonists is to prevent the release of LH during COS. In contrast, the LH-lowering effect of GnRH agonists develops over a number of days. GnRH antagonists are traditionally given, starting after 5th -7th day of gonadotropin stimulation. However, when this is done in older women and those (regardless of age) who have DOR, LH-suppression might be reached too late to prevent the deleterious effect of excessive ovarian androgen production on egg development in the early stage of ovarian stimulation. This is why, it is my preference to administer GnRH-antagonists, starting at the initiation of gonadotropin administration.
Estrogen Priming has succeeded in significantly enhancing ovarian response to gonadotropins in many of otherwise very poor responders.
With ovulation induction using fertility drugs, the administration of 10,000U hCGu (Pregnyl; Profasi, Novarel) or 500mcg hCGr (Ovidrel/Ovitrel) “trigger”) sends the eggs (into maturational division (meiosis). This process is designed to halve the chromosome number, resulting in mature eggs (M2) that will have 23 chromosomes rather that the 46 chromosomes they had prior to the “trigger”. Such a chromosomally numerically normal (euploid), mature (MII) eggs, upon being fertilized will (hopefully) propagate euploid embryos that have 46 chromosomes and will be “: competent” to propagate viable pregnancies. In my opinion, the key is to always “trigger” with no less than 10,000U of hCGu or 500mcg hCGr (Ovidrel/Ovitrel). Any lesser dosage often will reduce the efficiency of meiosis and increase the risk of the eggs being aneuploid. I personally do not use the agonist (Lupron) “trigger”, unless it is combined with (low dosage) hCG. The supposed reason for using the agonist, (Lupron) “trigger” is that by inducing meiosis through compelling a surge in the release of LH by the pituitary gland, the risk it reduces the risk of OHSS. This may be true, but it comes at the expense of egg quality because the extent of the induced LH surge varies and if too little LH is released, meiosis can be compromised, thereby increasing the likelihood of aneuploid and immature (MI) eggs. And there are other better approaches to preventing OHSS (e.g. “prolonged coasting”), in my opinion.
In natural (unstimulated) as well as in cycles stimulated with fertility drugs, the ability of follicles to properly respond to FSH stimulation is dependent on their having developed FSH-responsive receptors. Pre-antral follicles (PAF) do not have such primed FSH receptors and thus cannot respond properly to FSH stimulation with gonadotropins. The acquisition of FSH receptor responsivity requires that the pre-antral follicles be exposed to FSH, for a number of days (5-7) during which time they attain “FSH-responsivity” and are now known as antral follicles (AF). These AF’s are now able to respond properly to stimulation with administered FSH-gonadotropins. In regular menstrual cycles, the rising FSH output from the pituitary gland insures that PAFs convert tor AF’s. The BCP (as well as prolonged administration of estrogen/progesterone) suppresses FSH. This suppression needs to be countered by artificially causing blood FSH levels to rise in order to cause PAF to AF conversion prior to COS commencing, otherwise pre-antral-to –antral follicle conversion will not take place in an orderly fashion, the duration of ovarian stimulation will be prolonged and both follicle and egg development may be compromised. GnRH agonists cause an immediate surge in release of FSH by the pituitary gland thus causing conversion from PAF to SAF. This is why women who take a BCP to launch a cycle of COS need to have an overlap of the BCP with an agonist. By overlapping the BCP with an agonist for a few days prior to menstruation the early recruited follicles are able to complete their developmental drive to the AF stage and as such, be ready to respond appropriately to optimal ovarian stimulation. Using this approach, the timing of the initiation of the IVF treatment cycle can readily and safely be regulated and controlled by varying the length of time that the woman is on the BCP. Since optimizing follicular response to COS requires that prior to stimulation with gonadotropins, FSH-induced conversion from PAF to AF’s first be completed and the BCP suppresses FSH, it follows when it comes to women launching COS coming off a BCP something needs to be done to cause a rise in FSH for 5-7 days prior to menstruation heralding the cycle of CO S. This is where overlapping the BCP with a GnRHa comes in. The agonist causes FSH to be released by the pituitary gland and if overlapped with the BCP for several days and this will (within 2-5 days) facilitate PAF to AF conversion…. in time to start COS with the onset of menstruation. Initiating ovarian stimulation in women taking a BCP, without doing this is suboptimal.
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