In order for any organism to attain an optimal state of maturation (ripening) it must first undergo full growth and development. A fruit plucked from a tree before having developed fully or a poorly developed fruit might still ripen (mature) on the shelf and might even appear as enticing as one that had previously undergone proper development, but it will lack the same quality. The same principles apply to the development and maturation of human eggs. Proper development as well as precise timing in the initiation of egg maturation with LH or hCG is no less crucial to optimal egg maturation, fertilization and ultimately to embryo quality. In fact, in cases where egg maturation is improperly timed (LH or hCG is released/given too early, i.e. prematurely or too late, i.e. post-maturely) there is an increased risk of aneuploidy (structural and numerical chromosomal abnormalities) leading to compromised reproductive performance.
The potential for a woman’s eggs to undergo orderly maturation, successful fertilization, and subsequent progression to “good quality embryos” that are “competent” (capable of producing healthy offspring), is in large part, genetically determined. However, the expression of such potential is profoundly susceptible to numerous extrinsic influences, especially to intra-ovarian hormonal changes during the pre-ovulatory phase of the cycle.
During the normal ovulation cycle, ovarian hormonal changes are orchestrated to avoid irregularities in production and interaction that could adversely influence follicle development and egg quality. As an example, while small amounts of ovarian male hormones (predominantly testosterone) are essential to enhance egg and follicle development, over-exposure to excessive amounts of the same hormones can seriously compromise egg (and subsequently, also embryo) quality. It follows that protocols for ovarian stimulation should be geared towards optimizing follicle and egg development while avoiding overexposure to ovarian male hormones. The fulfillment of these objectives requires a very strategic and individualized approach to ovarian stimulation and precise timing of the human chorionic gonadotropin (hCG) “trigger.”
It is important to recognize that the pituitary gonadotropins, LH and FSH, while both playing a pivotal role in follicle development, have different primary sites of action in the ovary. The action of FSH is mainly directed at the cells that line the inside of the follicles (i.e. granulosa cells). LH, on the other hand, acts primarily on the connective tissue that surrounds the follicles (i.e. the ovarian stroma or theca) to compel the production of male hormones.. Some LH is essential because it is the androgens (mainly testosterone) that serves as th building block upon which FSH acts to promote follicle growth, estrogen production and egg development. Without some LH-induced testosterone production egg and follicle development would indeed be compromised. However, only a small amount testosterone is necessary for optimal development. Over-exposure to such androgens has a detrimental effect on granulosa cell estrogen production, follicle growth/development, egg maturation, fertilization potential and subsequent embryo chromosomal integrity (“competency” Furthermore, excessive ovarian androgens can also compromise estrogen-induced endometrial growth and development leading to a thin and unreceptive uterine lining, sometimes seen in women with PCOS who usually have excessive ovarian LH-induced testosterone production..
In conditions such as polycystic ovarian syndrome (PCOS), which is characterized by increased blood LH levels, there is also an increased ovarian androgen production. It is therefore not surprising that “poor egg/embryo quality” and inadequate endometrial development are often features of this condition. The use of LH-containing preparations such as Menopur might further aggravate this effect. Thus we strongly recommend against the exclusive use of such products, in PCOS patients, preferring FSH-dominant products such as Follistim, Puregon and Gonal F. While it would seem prudent to limit LH exposure in all cases of ovarian stimulation, this appears to be more relevant in older women, who tend to be more sensitive to LH
Preparing for Ovarian Stimulation:
Before embarking on ovarian stimulation it is essential to try and define the woman’s ovarian reserve (i.e., the number of eggs still available in her ovaries). Determination of the ovarian reserve will assist in defining the protocol of ovarian stimulation that would most safely yield the optimum number and quality of follicles/eggs in a given case. The ovarian reserve can best be assessed by determining the woman’s blood FSH and estradiol (E2) measurement on the 3rd day of a spontaneous menstrual cycle and by evaluating the manner in which she responded to a most recent cycle of treatment. Other blood tests that can also be selectively used to assist in assessing ovarian reserve are measurement of blood antimullerian hormone and inhibin B levels.Once the ideal stimulation protocol is selected, the next step is to choose a suitable time for IVF treatment. For women who require a repeated cycle it is advisable that at least one-month be allowed to elapse (“resting cycle”) between IVF treatments, in order to allow the ovaries to fully recover from the preceding stimulation. Since estrogen or a combined BCP suppresses LH, it is both clinically beneficial as well as convenient to launch IVF cycles with the woman having been on at least 10 days of combined birth control pill (BCP) such as Desogen, Low-estrin or Marvelon.
Does the BCP suppress ovarian response to COS? One often hears the expressed opinion that the BCP suppresses response to ovarian stimulation. This is not the case, provided that the BCP is overlapped with administration of an agonist (e.g. Lupron, Buserelin, Superfact) for several days leading up to the start of menstruation and the initiation of ovarian stimulation cycle with gonadotropin drugs. If the latter precaution is not taken, and the cycle of stimulation is initiated coming directly off the BCP the response will often be blunted and subsequent egg quality could be adversely affected. The explanation for this is that 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 PAPs 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 and the follicles will not readily respond to gonadotropins (FSH) , thereby delaying follicle development by up to 7 days and compromising egg quality. GnRH agonists (e.g. Lupron, Buserelin, Superfact) , 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.
The baseline ultrasound examination: It is also important that there be no functional ovarian cysts at the time ovarian stimulation commences. To insure this, the patients can undergo an ultrasound examination at or near the onset of menses immediately prior to initiating ovarian stimulation. At the onset of bleeding a measurement of blood estradiol (E2) is done to insure that it is low enough (under 70 pg/ml) to start administering the fertility drugs. The commonest cause of an elevated blood E2 level around this time is the existence of one or more ovarian follicular cysts. These should be allowed to absorb, or be aspirated as soon as possible (I personally prefer to aspirate cysts under local anesthesia, on the spot COH.
Unlike GnRH agonists that exert their LH (and FSH) lowering effect by exhausting the pituitary gland of its over 4-7 days GnRH antagonists (such as Ganirelix, Orgalutron, Cetrotide ) do so directly and immediately (within a few hours of administration).Thus both agonists and antagonists of GnRH both serve to establish a “low LH environment” in which follicular and egg development can proceed optimally.
The Choice of Gonadotropin Products to be Prescribed:The recent availability of DNA-recombinant FSH and LH gonadotropins has made this an easy choice. In my opinion, it is no longer necessary to prescribe urinary-derived gonadotropins where there could be significant variations in batch to batch biological potency and thus in response to stimulation. There is also (in my opinion) little advantage in using combined FSH/LH urinary-derived products where the additional LH contained in the preparation might in some cases compromise rather than enhance follicle and egg development. Accordingly, with few exceptions I personally only advocate the use of pure DNA-recombinant FSH (Follistim, Puregon and Gonal-F) and low dosage menotropins (Menopur) for my IVF patients. The exception to this rule is when it comes to prescribing an hCG product. Here I advocate the use of 10,000U urinary-derived hCG (Profasi, Pregnyl and Novarel) or 500mcg recombinant hCG (Ovidrel).
OVARIAN STIMULATION PROTOCOLS:
· Long GnRH Agonist Protocols: The most commonly prescribed protocol for agonist/gonadotropin administration is the so-called “long protocol”. An agonist (usually, Lupron) is given either in a natural cycle, starting a 5-7 days prior to menstruation or is overlapped with the BCP for two days whereupon the latter is stopped and the Lupron, continued until menstruation ensues. The agonist precipitates a rapid rise in FSH and LH level, which is rapidly followed by a precipitous decline in the blood level of both, to near zero. This is followed by uterine withdrawal bleeding (menstruation) within 5-7 days of starting the agonist treatment, whereupon gonadotropin treatment is initiated (preferably within 7-10 days of the onset of menses) while daily Lupron injections continue, to ensure a relatively “low LH- environment”. Gonadotropin administration continues until the hCG trigger.
· Short (“Flare”) GnRH-agonist (GnRHa) Protocol: Another GnRHa usage for COS is the so called “(micro) flare protocol”. This involves initiating gonadotropin therapy commensurate with initiation of gonadotropin administration. The supposed objective is to deliberately allow Lupron to elicit an initial surge (“flare”) in pituitary FSH release in order to augment FSH administration by increased FSH production. Unfortunately, this “spring board effect” constitutes “a double-edged sword”. While it indeed increases the release of FSH, it at the same time causes a surge in LH release. The latter can evoke excessive ovarian stromal/thecal androgen production which could potentially compromise egg quality, especially when it comes to older women and women with DOR. I am of the opinion that by evoking an exaggerated ovarian androgen response, such “(micro) flare protocols” can harm egg/embryo quality and reduce IVF success rates, especially when it comes to COS in older women, and in women with diminished ovarian reserve. Accordingly, I do not prescribe such protocols to my IVF patients
· Long-Agonist/Antagonist Conversion Protocol (A/ACP): With a few (notable) exceptions I preferentially advocate this protocol for many of my patients. With the A/ACP, as with the long protocol (see above) the woman again prepares to launch her stimulation cycle by taking a BCP for at least ten days before overlapping with an agonist such as Lupron. However, when about 5-7 days later her menstruation starts, she supplants the agonist with a half dosage (125mg) of an antagonist (e.g. Ganirelix, Orgalutron or Cetrotide).Within a few days of this switch-over, gonadotropin stimulation is commenced. Both the antagonist and the gonadotropins are then continued until the hCG trigger. The purpose in switching from agonist to antagonist is to intentionally allow only a very small amount of the woman’s own pituitary LH to enter her blood and reach her ovaries, while at the same time preventing a large amount of LH from reaching her ovaries. This is because while a small amount of LH is essential to promote and optimize FSH-induced follicular growth and egg maturation, a large concentration of LH can trigger over-production of ovarian stromal testosterone, with an adverse effect of follicle/egg/embryo quality. Moreover, since testosterone also down-regulates estrogen receptors in the endometrium, an excess of testosterone can also have an adverse effect on endometrial growth. Also, since agonists might suppress some ovarian response to the gonadotropin stimulation, antagonists do not do so. It is for this reason that the A/ACP is so well suited to older women and those with some degree of diminished ovarian reserve.
· Agonist/antagonist conversion protocol with estrogen priming: Women who have a significant degree of diminished ovarian reserve are first given GnRH agonist for a number of days to effect pituitary down-regulation. Upon post-BCP/agonist-induced menstruation, the dosage of GnRH agonist is drastically lowered (or commonly is supplanted by 125mg daily of an antagonist) and the woman is given twice-weekly injections of 2-4mg of estradiol valerate (E2V) for a period of 7-10 days. Ovarian stimulation is then initiated using a relatively high dosage of an FSH-dominant gonadotropins such as Follistim, Puregon or Gonal F for a few days, whereupon the dosage is reduced and a small amount of DNA-recombinant LH (Luveris) is added daily. Both the FSH and the LH are then continued along with daily administration of GnRH agonist (or antagonist) until the “hCG trigger”. The reason for the “estrogen priming” is because it enhances follicle response to FSH and also helps optimize the uterine lining. There is one potential drawback to the use of the A/ACP. We have learned that prolonged use of a GnRH antagonist throughout the ovarian stimulation process can compromise the predictive value of serial plasma E2 measurements to evaluate follicle growth and development. It appears that when the antagonist is given throughout stimulation, the blood E2 levels tend to be significantly lower than when the agonist alone is used or where antagonist treatment is only commenced 5-7 days into the ovarian stimulation process. The reason for this is presently unclear. Accordingly, when the A/ACP is employed, we rely more on follicle size monitoring than on serial blood E2 trends to assess progress. Also, younger women (under 30 years) and women with absent, irregular or dysfunctional ovulation, and those with polycystic ovarian syndrome are at risk of developing life-threatening Severe Ovarian Hyperstimulation Syndrome (OHSS). The prediction of this condition requires daily access to accurate blood E2 levels. Accordingly we currently tend to refrain from prescribing the A/ACP in such cases, preferring instead use the “standard long-protocol” approach.
· Short-GnRH antagonist protocols: The use of GnRH antagonists as currently prescribed in ovarian stimulation cycles (i.e. the administration of 250mcg daily starting on the 6th or 7th day of stimulation with gonadotropins) may be problematic, especially in women over 39 yrs., women with diminished ovarian reserve (i.e. “poor responders” to gonadotropins), and women with PCOS. Such women tend to have higher levels of LH to start with and as such the initiation of LH suppression with GnRH antagonists so late in the cycle (usually on day 6-7) of stimulation fails to suppress LH early enough to avoid compromising egg development. This can adversely influence egg/embryo quality and endometrial development. As is the case with the “microflare” approach (see above) the use of GnRH antagonist protocols in younger women who have normal ovarian reserve, is acceptable. Again, for reasons of caution, and because I see no benefit in doing so, I personally never prescribe this approach for my patients. Presumably, the reason for the suggested mid-follicular initiation of high dose GnRH antagonist is to prevent the occurrence of the so called “premature LH surge”, which is known to be associated with “follicular exhaustion” and poor egg/embryo quality. However the term “premature LH surge” is a misnomer and the concept of this being a “terminal event” or an isolated insult is erroneous. In fact, the event is the culmination (end point) of the progressive escalation in LH (“a staircase effect”) which results in increasing ovarian stromal activation with commensurate growing androgen production. Trying to improve ovarian response and protect against follicular exhaustion by administering GnRH antagonists during the final few days of ovarian stimulation is like trying to prevent a shipwreck by removing the tip of an iceberg.
· Short-GnRH-agonist (“micro-flare”) protocols: Another approach to COH is by way of so-called “microflare protocols”. This involves initiating gonadotropin therapy simultaneously with the administration of GnRH agonist. The intent is to deliberately allow Lupron to affect an initial surge (“flare”) in pituitary FSH release so as to augment ovarian response to the gonadotropin medication. Unfortunately, this approach represents “a double edged sword” as the resulting increased release of FSH is likely to be accompanied by a concomitant (excessive) rise in LH levels that could evoke excessive production of male hormone by the ovarian stroma. The latter in turn could potentially compromise egg quality, especially in women over 39 years of age, women with diminished ovarian reserve, and in women with polycystic ovarian syndrome (PCOS) – all of whose ovaries have increased sensitivity to LH. In this way, “microflare protocols” can potentially hinder egg/embryo development and reduce IVF success rates. While microflare protocols usually are not harmful in younger women and those with normal ovarian reserve, I personally avoid this approach altogether for safety sake. The follicles/eggs of women on GnRH-agonist “micro-flare protocols” can be exposed to exaggerated agonist-induced LH release, (the “flare effect”) while the follicles/eggs of women, who receive GnRH antagonists starting 6-8 days following the initiation of stimulation with gonadotropins can likewise be exposed to pituitary LH-induced ovarian male hormones (especially testosterone). While this is not necessarily problematic in younger women and those with adequate ovarian reserve (“normal responders”) it could be decidedly prejudicial in “poor responders” and older women where there is increased follicle and egg vulnerability to high local male hormone levels.
· The “Trigger Shot”- A Critical Decision: The egg goes through maturational division (meiosis) during the 36 hour period that precedes ovulation or retrieval. The efficiency of this process will determine the outcome of reproduction. It follows that when it comes to ovulation induction, aside from selecting a suitable protocol for COS one of the most important decisions the clinician has to make involves choosing and implementing with logic and precision, the “trigger shot” by which to facilitate meiosis.
· Urinary versus recombinant hCG: Until quite recently, the standard method used to initiate the “trigger shot” was through the administration of 10,000 units of hCGu. More recently, a recombinant form of hCGr (Ovidrel) was introduced and marketed in 250 mcg doses. But clinical experience strongly suggests that 250 mcg of Ovidrel is most likely not equivalent in biological potency to 10,000 units of hCG. It probably at best only has 60%of the potency of a 10,000U dose of hCGu and as such might not be sufficient to fully promote meiosis, especially in cases where the woman has numerous follicles. For this reason, I firmly believe that when hCGr is selected as the “trigger shot” the dosage should be doubled to 500 mcg, at which dosage it will probably have an equivalent effect on promoting meiosis as would 10,000 units of hCGu.
· The dosage of hCG used: Some clinicians, when faced with a risk of OHSS developing will deliberately elect to reduce the dosage of hCG administered as a trigger in the hope that by doing so, the risk of developing critical OHSS will be lowered. It is my opinion that such an approach is not optimal because a low dose of hCG (e.g., 5000 units hCGu or 25omcg hCGr) is likely inadequate to optimize the efficiency of meiosis, particularly when it comes to cases such as this where there are numerous follicles. In my opinion a far better approach is to use a method that I first described in 1989, known as “prolonged coasting”
· Use of hCG versus a GnRHa (e.g., Lupron/Buserelin/Superfact) as the trigger shot: It has been suggested that the use of an “agonist ( Lupron) trigger” in women at risk of developing severe ovarian hyperstimulation syndrome (OHSS) could potentially reduce the risk of the condition becoming critical and thereby placing the woman at risk of developing life-endangering complications. It is for this reason that many RE’s prefer to trigger meiosis in this way (using an agonist-Lupron) rather than through the use of hCG. The agonist promptly causes the woman’s pituitary gland to expunge a large amount of LH over a short period of time and it is this LH “surge” that triggers meiosis. The problem with this approach, in my opinion, is that it is hard to predict how much LH will be released in by the pituitary gland of a given patient receiving an agonist trigger shot, especially if the woman was down-regulated using an agonist, or in cases where an antagonist was used to block pituitary LH release. For this reason, I personally prefer to use hCGu for the trigger, even in cases of ovarian hyperstimulation, with one important proviso…that she underwent “prolonged coasting” in order to reduce the risk of critical OHSS prior to the 10,000 unit hCGu “trigger”.
· Combined use of hCG +GnRHa; This approach is preferable to the use of a GnRHa , alone. However, in my opinion is inferior to the appropriate and correct use of hCG, alone.
· The timing of the trigger shot to initiate meiosis: This should coincide with the majority of ovarian follicles being >15 mm in mean diameter with several follicles having reached 18-22 mm. Follicles of larger than 22 mm will usually harbor overdeveloped eggs which in turn will usually fail to produce good quality eggs. Conversely, follicles less than 15 mm will usually harbor underdeveloped eggs that are more likely to be aneuploid and incompetent following the “trigger”.
Severe Ovarian Hyperstimulation Syndrome (OHSS) and prolonged Coasting”
OHSS is a life-endangering condition that usually occurs in women undergoing COS where the blood E2 level rises to above 4,000pg/ml. The risk escalates to greater than 80% in cases where the E2 level rises above 6,000pg/ml. It rarely occurs in normally ovulating women or older (>39Y) women and is more commonly encountered in:
· Young women (under 30y) who have a high ovarian reserve (based upon basal FSH and AMH.
· Women with polycystic Ovarian Syndrome ( PCOS)
· Non-PCOS women who do not ovulate spontaneously
The treating physician should be alerted to the possibility of hyperstimulation when when encountering a woman who develops >25 ovarian follicles of 14mm-16mm in mean diameter, in association with a blood E2 level of above 2,5000pg/ml prior to the hCG “trigger”.
OHSS is a self-limiting condition. Its development is linked to the effect of hCG and thus does not occur until the “hCG trigger” is administered. In fact, there is virtually no risk of OHSS until the hCG “trigger” is administered.
“Prolonged Coasting” is a procedure I introduced in 1991. It involves abruptly stopping gonadotropin therapy while continuing to administer the GnRH agonist (e.g. Lupron, Buserelin) deferring the hCG “trigger” until the woman is out of risk (as evidenced by a fall in plasma estradiol level to below 2,500pg/ml).
It is important that “prolonged coasting” be initiated as soon as two or more follicles have attained a greater diameter than 18mm with at least 50% of the remaining follicles having attained 14-16mm. To start the process of “prolonged coasting” any earlier or any later, while it would still protect against the development of OHSS, would almost certainly result in compromised egg and embryo quality with ultimate failure of the IVF cycle. Simply stated, the precise timing of initiating the process is critical. Proper implementation of PC will almost always prevent OHSS without seriously compromising egg/embryo quality.