Female Fertility Testing
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Types of Female Fertility Tests
Ovarian Reserve Testing
Almost one in ten women who present for infertility treatment will have such poor ovarian function that they are extremely unlikely to achieve pregnancy. Currently, there is no way to correct this problem, and so assessment ovarian function can be most important fertility test that a physician does.
Ovarian reserve testing is not the same thing as testing for ovulation. Normal ovulation and regular menstrual cycles can exist while still having a poor potential for pregnancy.
Ovarian reserve
A person is born with all the eggs they are ever going to produce. By the time of birth, the ovarian reserve – the number of remaining eggs stored in the follicles – will have decreased dramatically. Over time, ongoing follicular depletion will continue to reduce the number of eggs remaining in the ovaries. In fact, far more eggs will be lost by degeneration than are lost by ovulation.
There are a few different tests that can assess ovarian reserve:
- AMH levels (Anti-Mullerian hormone): Measurement of the hormone AMH in the blood.
- Clomid Challenge Test: Assessment of FSH levels in the blood before and after taking a medication called Clomid.
- Ovarian Volume Assessment: The size of the ovaries can predict pregnancy potential.
- Antral Follicle Counts: Counting follicles seen by ultrasound can predict ovarian reserve.
Ovarian volume Assessment
As we learned previously, eggs degenerate as a person ages. Tens of thousands of eggs are lost every year of a person's life. This is one of the main reasons why fertility decreases with age.
As the eggs degenerate, the ovaries become smaller. Using transvaginal ultrasound, the volume of each ovary can be calculated by measuring the length, width and depth.
Once you know the ovarian volume, ovarian reserve, ovary size, and time to menopause, you can calculate a person's “reproductive age.” Someone's reproductive age may be older or younger than their actual age.
For example, a 35-year-old with very small ovaries may have the reproductive age of a 40-year-old. Alternatively, a 40-year-old with very large ovaries may have the reproductive age of a 35-year-old.
Medical studies have correlated ovarian size with an individual's ability to respond adequately to fertility medications. Those with small ovaries tend to respond more poorly to fertility medications than those with larger ovaries. Studies have also correlated IVF pregnancy rates with ovarian volume.
Assessment of ovarian reserve by antral follicle count
A third reliable method for ovarian reserve testing also uses transvaginal ultrasound. This method is known as the antral follicle count.
Follicles are the name given to the small ovarian cysts that contain eggs. At the beginning of a menstrual cycle, using ultrasound we can visualize and even measure these follicles in the ovary. A normal follicle will be less than 9 or 10 mm in diameter.
Studies have now demonstrated that the number of these follicles that are visible at the beginning of the menstrual cycle decreases significantly with age. It likely represents a decrease in the number of viable eggs remaining in the ovary.
In addition, younger people with decreased ovarian reserve may have a smaller number of these follicles. This is demonstrated by the fact that individuals with a diminished antral follicle count respond poorly to fertility medications, have a greater likelihood of having IVF cycles cancelled for poor response, and when they do complete IVF cycles, their pregnancy rates are lower.
Studies differ on the exact number of follicles that would be considered decreased but most would be in agreement that a total number of less than four is very low and therefore predictive of decreased ovarian reserve.
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Schedule a ConsultationQuestions About Ovarian Reserve Testing & The AMH Process
Unfortunately, this is probably not true. Elevations in FSH levels when performed at the proper time of the cycle are reflective of decreased ovarian reserve. This occurs from a decreased number of viable eggs remaining in the ovaries or from a fundamental change within the egg cells themselves that make them less likely to produce normal viable embryos.
While some evidence suggests that acupuncture may improve blood flow to the uterus or ovaries, it is very unlikely that increased blood flow will make any difference. It cannot, for example, cause new eggs to be made in the ovaries or change their internal structure.
While it may be possible to change the FSH level itself by taking small amounts of estrogen, this does not result in a change in the potential to produce pregnancy. Remember, the FSH levels are not causing the problem -- they merely reflect that there is a problem. By manipulating the FSH levels, all you do is eliminate it as a means for being a useful measure of ovarian function.
Herbal remedies are similarly ineffective. Herbals are very complex mixtures of chemicals derived from from various plant sources. Many of these chemicals will have hormonal activity in the body and may mimic the actions of estrogen, progesterone, or other hormones. As such, it is possible for herbals to affect a woman’s FSH level. However, as with the case for acupuncture, they are not changing the ovarian function itself. A reduced FSH level does not indicate that the ovaries are now more capable of producing pregnancy. Furthermore, since herbals are not regulated or controlled in the United States, there is no way to determine exactly what they contain or what you are putting in your body.
The answer to this question is not known for certain. However, there does appear to be some evidence that individuals with decreased ovarian reserve as measured by an elevated FSH or abnormal clomid challenge test are at increased risk for having babies with chromosomal abnormalities.
One study looked at women with normal FSH levels and compared them to those with elevated levels. Over a six month period, if they had a miscarriage, chromosome testing was performed on the fetal tissue. The testing found that women with high FSH levels had more fetuses with chromosomal abnormalities.
Another study followed over 1,000 women with high FSH levels who tried to attempt pregnancy with their own eggs. Only 28 of them achieved pregnancy and of those, 20 miscarried. This is a much higher miscarriage rate than would have been expected based on the ages of these women. Since chromosomal abnormality is the most common cause for miscarriage, it is likely that these women had more fetuses with chromosomal abnormality.
The final piece of evidence comes from patients who have undergone in vitro fertilization – IVF with preimplantation genetic testing (PGT) of their embryos. Those who have high FSH levels have a higher percentage of embryos with chromosomal abnormalities when compared to those with normal FSH levels.
All hormone levels fluctuate. As a person ages, the monthly fluctuations in FSH levels will become more and more pronounced. At a certain point, these levels may peak into an abnormally high range. Eventually, the FSH levels will be consistently elevated. Good data now exists to suggest that by the time these fluctuations have caused FSH levels to be sporadically elevated, fertility has already significantly declined. This means that FSH elevation, even sporadic elevation, is a relatively late sign of decreased fertility. While pregnancy at this point is not impossible, it is far less likely to occur.
A Canadian study of IVF patients compared three groups:
- Consistently normal FSH levels
- Sporadically elevated levels
- Persistently elevated levels
Those with consistently normal levels had good pregnancy rates. On the other hand, those with sporadically elevated levels and persistently elevated levels had the same very low pregnancy rates.
For the last several years, there has been a large amount of interest in a hormone called Anti-Müllerian hormone (AMH) as a measure of ovarian reserve. Some older studies referred to this hormone as Müllerian inhibiting substance (MIS) or factor (MIF). They are all names for the same hormone.
In men, AMH is produced only in the testicles, and in women it is produced only in the ovaries. This article will focus on using blood AMH levels as an indicator of ovarian reserve.
Ovarian reserve is a term used by fertility specialists to estimate the chances for having a healthy live born baby using the individual's own eggs. To understand how AMH works as an indicator of ovarian reserve, it is important to first understand a little about how the eggs are stored in the ovary. Early in pregnancy, a female fetus starts to form eggs in the ovaries. Each egg is surrounded by a group of cells called granulosae cells. The eggs and its surrounding granulosae cells are collectively referred to as a follicle.
As the female fetus matures, more follicles are produced. At about the 20th week of pregnancy, the female fetus now has several million follicles. At that point however, the fetus stops making new follicles and the existing follicles start to degenerate. By the time a female is born, the number of follicles has dropped to only a few hundred thousand. After birth, the follicles continue to degenerate. This process of degeneration is constant and will continue until there are no follicles (eggs) remaining in the ovary.
Just prior to puberty, the follicles will start to develop to prepare for the initiation of ovulation, known as folliculogenesis. Folliculogenesis lasts for approximately 375 days and coincides with thirteen menstrual cycles. The process is continuous, so at any given moment, a person will have follicles at various stages of development in their ovaries.
Follicle stages
Primordial: This is the only type of follicle present in the fetus. The majority of follicles in the adult ovary are in the primordial stage, during which the follicles are very small and cannot be seen on ultrasound. The eggs are immature. Theses follicles are dormant and can remain dormant for up to 50 years in humans, and they do not respond to hormones. At some point, the primordial follicles are “awakened," a process that is not fully understood yet. AMH is not produced by primordial follicles.
Primary: Once a primordial follicle is awakened, it is known as a primary follicle. The egg begins on a 375 day journey toward either ovulation or destruction. Primary follicles are not responsive to hormones, not seen on ultrasound, and they do not produce AMH.
Secondary: Approximately 290 days of growth and development after the primordial follicle is awakened, the primary follicle will become a secondary follicle. At the end of this stage, the follicle starts to produce AMH and is referred to as a pre-antral follicle. While still too small to see on ultrasound, these follicles will now respond to hormones. A pre-antral follicle is about 0.2 mm in diameter and is about 65 days away from ovulation.
Antral: This stage lasts about 50 days, during which the egg and follicle grow and develop. Antral follicles are visible on ultrasound and range in size from 2-10 mm. The antral follicles are counted during an ultrasound to form the basis of another ovarian reserve test. At any given moment, an individual may have only a few antral follicles or a large number. This group of antral follicles is known as a cohort. The size of the cohort will rarely exceed 50 or 60 follicles and is often less.
Antral follicles produce AMH as well as estrogen. Receptors on the surface of the granulosae cells of the antral follicle are very sensitive to hormone stimulation from the pituitary especially FSH (follicle stimulating hormone). FSH causes the follicles to produce increasing amounts of estrogen. Both estrogen and FSH are necessary for continued development of the follicle. Typically, only one follicle from the group will become dominant and proceed towards ovulation, the rest will degenerate. The dominant follicle and the degenerating follicle have stopped producing AMH.
Pre-ovulatory – By 8-10 days before ovulation, one dominant follicle will have been selected for continued development. A pre-ovulatory follicle will eventually reach a size of 20–22 mm just prior to ovulation.
Remember: AMH is produced solely in the granulosae cells of pre antral and antral ovarian follicles. Measuring the AMH levels gives an indication of the size of the cohort.
AMH decreases with age
With age, the pool of primordial follicles shrinks due to degeneration. As a result, the number of follicles which are awakened from the dormant state decreases. As the size of the cohort of antral follicles decreases, the total amount of AMH produced by those follicles also decreases. Thus, older people will have lower AMH levels than younger ones.
Although people in each age group can have a range of AMH levels, the average AMH level in younger patients is higher than the average level in older ones. The older the group studied, the lower the average AMH.
A younge patient with a very low AMH may have a similar level to the average older patient.
Examples:
An 18-year-old has an AMH of 1.0 -- a poor ovarian reserve compared to others her age. An AMH less than 1.10 means that 905 of patients the same age have a better AMH level.
a 32-year-old with an AMH of 2.1 would be considered average in that age group. 50% of patients in that age category have a better AMH and 50% have a worse AMH.
A 40-year-old with an AMH of 3.2 has a much better ovarian reserve than others her age.
Remember: The number of antral follicles (the cohort) size, correlates with fertility potential. Young women, who normally have better fertility, will normally have a larger number of antral follicles visible on ultrasound and higher AMH levels.
AMH and ovarian reserve
The central concept for the measurement of blood levels of AMH to determine ovarian reserve is this: women with lower AMH levels have a lower ovarian reserve than women with high AMH levels. AMH is currently being used by fertility specialists to help predict women who may respond poorly to fertility medications and in general, couples who are less likely to be successful with fertility treatment.
AMH and fertility
Up until recently, most of the research into AMH involved women who had already been diagnosed with infertility. It was unclear whether AMH was a good predictor of pregnancy in patients who were just starting to attempt pregnancy. A recent study found, however, that in a group of women without infertility, those with a low AMH became pregnant less frequently than those with a higher AMH.
AMH and fertility treatment
Those with poor ovarian reserve as evidenced by a low AMH do not respond as well to fertility medications. These patients are known as poor responders. Even with the use of aggressive medication protocols using high doses of fertility medications, there is a poor response, and as a result, there is a high rate of treatment cancellation due to poor or absent response.
Even when eggs are stimulated to develop, the quality of those eggs seems worse. For example, in IVF1's program, women with an AMH less than 0.5 do not reach embryo transfer one-third of the time. Women with an AMH level over two, however, will have an embryo transfer 99% of the time.
If we look only at patients who were able to have an embryo transfer, those with an AMH less than 0.5 had a pregnancy rate of 18%, while those with a level over 2.0 had a pregnancy rate of 45%. This indicates abnormality in the eggs of patients with poor ovarian reserve.
Remember: A low AMH indicates a problem in both the quantity and quality of the remaining eggs.
Some other facts about AMH
AMH levels show much less fluctuation over the course of the menstrual cycle compared to other measures of ovarian reserve, such as the FSH blood test. However, there is some fluctuation -- the higher the AMH level, the greater the percentage of fluctuation can be seen.
Obese patients tend to have lower AMH levels. It is not clear why this occurs. It is known that obese women have poorer fertility than normal weight women; it is possible that the reason is due to poorer ovarian reserve.
Patients with PCOS commonly have a large pool of antral follicles, therefore they often have higher than normal AMH levels.