Jean-Claude Emperaire1
(1)
Bordeaux, France
The ovary is hardly an isolated organ. It is not only unique to each patient; it is subject to numerous intrinsic and extrinsic factors of the patient’s health and disease, as well as to personal and psychosocial environments.
4.1 Searching for Other Hypofertility Factors
Ovulatory stimulation using gonadotropins is a powerful treatment, to be initiated only with sage advice. A complete and thorough preliminary assessment is mandatory to identify and eliminate other factors that may be impeding a couple’s fertility or the efficacy of a treatment plan.
A proper evaluation must include:
· A clear hysterosalpingogram, to appraise utero-adnexal integrity. If patency of one or both tubes remains doubtful, a selective salpingogram should be performed. Should the procedure be technically impossible, or if a tubal obstruction is confirmed. Direct visualization also affords the opportunity to search for abnormalities such as adhesions or parietal endometriosis that may be missed by ultrasound scanning. When the integrity of the uterine cavity is doubtful, hysterosonography will confirm or eliminate the need for a hysteroscopy.
· An evaluation of the male partner’s fertility based upon a spermiogram and, when possible, supplemented by a post-coital test with spontaneous or estrogen-treated cervical mucus.
It bears noting that discovery of some abnormal findings during these initial explorations does not necessarily obviate ovulation stimulation, but it nevertheless suggests that some additional issues should be considered when developing a therapeutic strategy. Correction of a secondary problem may improve chances for clinical success.
4.2 Evaluation of the Patient
A patient’s age and body mass index (BMI) are certainly two of the more obvious characteristics relevant to success of ovulation induction. However, one must take into account a variety of related malfunctions or ongoing medical treatments.
4.2.1 Patient Age
A relatively advanced age should not automatically eliminate every candidate for ovarian stimulation, provided that FSH levels are not continually elevated. To be sure, numerous experimental studies of donor insemination and IVF have documented the progressive decline of pregnancy rates past the age of 38, even with a satisfactory process of ovulation induction, so age must always be a consideration. There are no reported studies of variations of the FSH threshold in relation to age, but a diminished ovarian response does appear more frequently in the late 30s and beyond, and higher FSH doses are typically needed with older patients. In addition, a substantial variation of individual responses to dosage may be encountered among older patients.
Advancing age does not necessarily alter the prognosis for a successful pregnancy in many types of anovulation. Indeed, time may actually become an ally in the patient of polycystic ovary syndrome. Pregnancy success rates with gonadotropin treatment actually increase in PCOS patients past the age of 36, possibly because of an age-related decrease in the size of the pre-antral follicular cohort.
4.2.2 Patient Weight
Ovulation stimulation should ideally be undertaken in patients within a normal BMI range of 20–25. Deviation from normal brings a variety of problems for a successful stimulation.
4.2.2.1 Insufficient Weight
Weight insufficiency usually occurs in a context of eating disorders that are associated with psychosocial problems. Decisions for stimulating ovulation in these cases should be taken judiciously, inasmuch as achieving a normal weight does not always restore spontaneous menstrual cycling. Ovarian stimulation can be a perplexing task in these low-weight patients because safety margins are narrower. Ovarian responses are somewhat more difficult to anticipate and stimulation should be attempted only when weight and psychological status are believed to have stabilized. Concurrence of a mental health professional should be obtained.
4.2.2.2 Excess Weight
A high proportion of anovulatory women present with weight excess. It is well established that the ovarian response to administered gonadotropins is blunted even when obesity is moderate (BMI < 28), perhaps due to a “depot” effect at the injection site in fat-infiltrated tissues combined with an increased volume of distribution. This would explain why increased dosing of gonadotropins, and/or prolonged duration of stimulation, is often necessary in the more obese patient, even when using the IM route: Bioavailability of injected FSH has been shown to be lower in these patients after SC administration than after IM injection [1]. For the same reasons, gonadotropins should be administered just above the knee when the SC route is chosen.
Spontaneous fertility is also lower in the more obese patient, and the risks for miscarriage and perinatal morbidity are higher. There is emerging evidence that leptin, a protein secreted by adipocytes, plays a key role in fertility, and elevated plasma levels are thought to disrupt folliculogenesis, steroid hormone secretion, and endometrial receptivity [2]. Although the overall success rates of obese patients are similar to those of normal weight women, at least in IVF trials, it remains important to attempt significant weight reduction prior to stimulation, using dietary or behavioral modification [3]. Indeed a weight loss of only 2–5 % has been reported sufficient for restoration of spontaneous ovulation within a few months in nearly half of anovulatory overweight patients [4].
All that said, it may be illusionary to hope for significant and stable weight loss in patients with a prolonged history of repeated weight losses and gains. Such a pattern frequently correlates with shifting phases of active to absent motivation about weight reduction, even when reinforced by an increased desire to become pregnant. Bariatric surgery may be cautiously considered in some instances. Because declining to help a patient with persistent obesity may represent for her yet another failure, it would be well advised to negotiate a “contract” of weight stability. By recording and discussing body weight during each monitoring appointment, one may pose the prospect of interrupting the stimulation protocol until the patient is able to return to a previously agreed weight. It is also important to refute the notion in the mind of heavy patients that “hormones put weight on.”
In patients with polycystic ovarian syndrome (PCOS), a peripheral insulin resistance is often encountered that leads to a hyperinsulinemia and an independent risk factor for obesity. Because weight loss, however difficult to achieve, may be necessary before embarking on ovarian stimulation, it may be advantageous to add metformin together with the stimulation itself [5]. Even if an obese patient succeeds in becoming pregnant, her excess weight adds additional risk to the pregnancy that is usually correlated with the degree of weight excess. Hypertension, diabetes, and perinatal complications can turn this apparent success into a very dismal outcome. Ovulation stimulation must be careful to avoid unreasonable and risky procedures.
4.2.2.3 Associated Pathologies
The prospect of ovarian stimulation and pregnancy provides a very appropriate time to heighten a patient’s awareness of the deleterious effects of alcohol, tobacco, and numerous other toxic substances on oocyte reserve and quality. It is also important to take into account a number of other associated risk factors before beginning the treatment:
· Chronic diseases: If one can establish that a given patient’s underlying chronic conditions such as a demyelinating syndrome, colorectal hemorrhage, epilepsy, or cardiovascular complications will likely be compatible with the prospect of a pregnancy, then the syndrome can be anticipated to be similarly compatible with protocols of ovarian stimulation. However, it is important to contact the patient’s specialist before beginning therapy in order to uncover potential hazards. For example, it is crucial to avoid all risk, however small it may be, for an ovarian hyperstimulation situation in a patient with an established coagulation disorder. Another example for caution would occur in a patient being treated for systemic lupus erythematosus, because her ovarian reserve may have been compromised even in the absence of alkylating treatment [6].
· Previous history of (extra-ovarian) cancer: It is difficult to comprehend why an oncologist would recommend against ovarian stimulation while still consenting to a pregnancy in a patient with a history of cancer. The levels of plasma estradiol resulting from a monofollicular stimulation protocol remain very close to those of the physiologic menstrual cycle. Even with a multifollicular protocol that might be used for IVF, the relatively high estradiol levels found during mid- to late follicular phase of a stimulated cycle are minimal compared to those which will flood a patient during the 9 months of pregnancy. This example of a “precaution principle” needs to be discussed each time with the patient’s oncologist in order to agree on the strategy best suited to the patient’s condition.
· Medications. Each patient’s therapies must be carefully evaluated, even if they do not appear as directly detrimental to ovarian stimulation, because it is also highly important to anticipate continued management of therapies once a pregnancy begins. This would be especially true for cytotoxic or psychoactive medications.
4.3 Evaluation of Ovarian Status
A thorough evaluation of the ovarian condition is a fundamental step. One must evaluate the complement of follicles, and thus the potential sensitivity to FSH and prognosis for stimulation. A woman’s oocyte reserve decreases steadily from intra-uterine life until menopause: from a mean of 100,000 at age 20–30,000 at age 30, and only 8,000 remaining at 40 years of age [7]. Although stem germ cells that appear capable of division and differentiation may be found in the adult female ovary, the reserve of primordial follicles must be considered as finite [8]. The ovarian endowment of oocytes should be assessed around the third day of the cycle (CD 2–5) using both ultrasound and hormonal measures.
4.3.1 Hormonal Parameters
4.3.1.1 FSH
Determination of plasma FSH remains a principal index, because levels increase as the follicular supply decreases. However the correlation between these two variables is far from tight, because FSH levels can fluctuate widely in blood. While a continuously elevated FSH level (>15 IU/l) is probably an early sign of ovarian insufficiency, moderately elevated FSH levels below 15 IU/l indicate only a need for a very cautious interpretation.
FSH secretion is pulsatile with peaks about every 90 min during the follicular phase. Thus a best evaluation of FSH should be performed on three pooled blood samples taken at 20 min intervals, a practice that is not routinely conducted. In addition, the normal range of plasma FSH varies between laboratories and also between hormone assay systems. Upper levels of normal can vary from 9.5 to 12 IU/l in individual laboratories.
While abnormally high FSH levels are usually confirmed by repeated observations in successive cycles, a pattern of normal FSH mixed interspersed with elevated readings should be taken as a warning for a declining ovarian reserve: in these cases, however, overall results from stimulations are not better when started on a cycle with a subnormal FSH value. Some patients with moderately elevated FSH (10–13 IU/l) demonstrate nevertheless a normal ability to achieve pregnancy on stimulation; this could reflect a physiological variation such as an FSH receptor polymorphism. Such a possibility must be kept in mind when working with young patients before considering oocyte donation. An attempt to stimulate follicular growth can still be carried out in these cases, although it may well require higher FSH doses in order to be successful.
On the other hand, levels of plasma FSH do not correlate well with oocyte quality. Fertility prognosis is actually better in women under 35 years of age and with moderately elevated FSH, compared to older women having FSH in the normal range [9]. Toner’s formula remains valid: FSH levels are a measure of oocyte quantity, whereas the patient’s age remains the best index of oocyte quality [10].
Use of dynamic assessments of FSH through administration of clomiphene or with a GnRH agonist in order to clarify the significance of borderline values are often disappointing, because of the intricacy of both the method and of its interpretation. In the end, the results are no more discriminating than by taking a single basal hormone measurement [11]. Similarly, the “Effort Test,” done by measuring estradiol secretion after FSH administration (a revival of the Netter test first described in 1968), is also disappointing [12]. These tests are better replaced by simply conducting an actual attempt to stimulate ovulation.
Estradiol. Isolated measures of estradiol alone are not very accurate markers of ovarian reserve, but are mandatory for the interpretation of the FSH level. Estradiol must be assayed at the same moment as FSH. An early developing ovarian insufficiency may be expressed with high estradiol values on CD 3 (>70 pg/ml) that will decrease and normalize FSH secretion via negative feedback.
Inhibin B. This glycoprotein of the TGF beta family is produced by the granulosa cells under the stimulating effect of FSH. It also inhibits pituitary secretion of FSH through a negative feedback mechanism. Because inhibin B levels move in the opposite direction of FSH, it was originally thought to be a reliable marker of ovarian reserve. However, a number of literature reports have described a fluctuating and poorly discriminating nature, and interest in its use as a marker of follicular reserve integrity has finally diminished.
Anti-Müllerian hormone (AMH). Another glycoprotein of the TGF-β family, AMH is presently considered as the best hormonal marker of ovarian reserve. Like Inhibin B, it is also produced by granulosa cells of primary follicles. Expression is highest in pre-antral and antral follicles, which then undergoes a gradual decline as the follicles mature further. AMH expression is highest in follicles of less than 4 mm in diameter, a size when they become sensitive to FSH, and the hormone serves to inhibit follicular transition from primordial to pre-antral stage. It also decreases the antral follicle sensitivity to FSH.
In contrast to other proposed hormonal markers, AMH secretion remains rather steady throughout the menstrual cycle. Some reports have suggested that levels decrease somewhat throughout the follicular phase and during multifollicular stimulation protocols, as the pre-antral and antral follicles grow larger and gradually cease secreting the hormone [13, 14]. Values are generally reproducible from one cycle to the next [15]. A level greater than 2 ng/ml is usually considered as evidence for a satisfactory ovarian reserve. However reports of substantial heterogeneity of quality of early AMH assay kits threw doubt on the validity of AMH values, and an abnormal value must always be considered with caution. Modified, improved assay procedures seem to have resolved much of the uncertainty at present, but are still lacking of an international standard [16]. AMH levels decline steadily during multifollicular stimulation in correlation with the rise of estradiol levels, confirming that growing follicles cease to secrete AMH [14]. On the other hand, it must be acknowledged that anti-Müllerian hormone has limited discriminative value concerning oocyte quality or regarding prospects for achieving a successful pregnancy [17]. On the other hand, AMH levels may be temporarily depressed by hormonal contraceptives, GnRH agonists, after pelvic surgery or in case of hypogonadotropic hypogonadism [18, 19].
To summarize, interpretation of these various hormonal values when attempting to estimate ovarian reserve, and also for devising treatment strategies for infertile couples, should nevertheless be taken with the benefit of hindsight and a great deal of caution, because they represent only statistical data that may not apply successfully to a particular patient [20]. In Hall’s retrospective study, for instance, half of the 78 patients who achieved pregnancy through IVF initially showed abnormally low values of both inhibin B and AMH [21].
4.3.2 Ultrasound Parameters
Ovarian follicle quantity. The technology involved in making antral follicle counts (AFC), usually conducted on the same cycle day that the hormonal measures are made, has been substantially improved with the latest generation of high frequency endovaginal probes that are capable of visualizing follicles as small as 2 mm diameter. Ultrasound now provides a direct view of the follicular cohort, but with some inter-cycle or inter-observer and intra-observer variations. Among the various hormonal parameters, plasma AMH correlates best with AFC as an indicator of the ovarian reserve [22]. Normally, the total AFC of visible structures at least 2 mm diameter is between 15 and 25 for the pair of “normofollicular” ovaries, although the number on each may not be equal. The capacity for an ovarian response to stimulation begins to decrease with AFC totals below 15, and it becomes problematic when fewer than five follicles are visible (“paucifollicular” ovaries) [23]. A higher number of follicles visible on each ovary (e.g., greater than 25) defines “multifollicular” and “micro-polycystic” conditions, and responses to gonadotropins may differ in these situations. Multifollicular ovaries show follicles of varied sizes distributed throughout the whole gonad, whereas the micro-polycystic ovary is characterized by the presence of numerous very small follicles squeezed together inside the ovarian cortex, and usually with a condensed ovarian stroma. These two conditions may be difficult to distinguish with certainty, particularly as the definitions of PCO remain imprecise. According to the most recent consensus conference, the visible follicles count necessary to establish a diagnosis continues to increase as technical sophistication of vaginal probes improves [22]. Three-dimensional ultrasound technology seems to offer little improvement for AFC protocols, which remains satisfactory by 2D imagery. In the end, it is simply the response of ovary itself, whether normal or explosive, to a conventional step up stimulation protocol, that makes the difference.
Follicular size. Measures of follicular size within the AFC are also significantly important, as smaller follicles (<5 mm) show a better predictive value than the larger ones (5–10 mm) [24].
Ovarian volume: Ovarian volume has also been proposed as a marker of ovarian reserve. While relatively easy to perform, this measure appears to provide little superior information than does the standard AFC [25].
4.3.3 Practical Indications for Evaluating Ovarian Reserve
Although assessment of ovarian reserve may not be always necessary, it is always useful prior to beginning treatment of an infertile couple.
Mono- or Paucifollicular Stimulation: A routine preliminary measure of the ovarian reserve markers would not appear to be mandatory for a patient under 35 years of age, unless she has a history of possible ovarian trauma (e.g., pelvic surgery or chemotherapy) or of endometriosis. It may become useful in cases when a younger patient has a poor response to an initial trial, or if a paucifollicular appearance is observed with ultrasound. On the other hand, an occasional young patient may show an already declining ovarian reserve, as this phenomenon is silent and can develop without apparent causes. Thus a growing number of clinicians recommend a routine assay of plasma AMH no matter the age of an infertile patient, and even in non-infertile patients who seek to delay their pregnancy for a later time [26]. Past the age of 35, evaluation of ovarian reserve becomes necessary in order to assess a possible alteration that would change the therapeutic strategy. For this evaluation the best combination is a measure of plasma AMH and the AFC, with measures of plasma FSH adding another prognostic factor when the initial two markers yield low values.
Multifollicular Stimulation. In this case, assessment of ovarian reserve is always necessary, whatever the patient’s age, in order to evaluate more precisely the follicular cohort size. This will help to establish a starting dose of gonadotropins and to anticipate the ovarian response. Here, too, AMH and AFC become the best choices, and are closely correlated, as they measure he same follicular pool; however, their performances characteristics are different and they cannot be really considered as interchangeable, AMH being at present the best measure of ovarian reserve and the most reliable predictive parameter of ovarian response [27].
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