Ovarian reserve tests are simple procedures that can tell a lot about reproductive potential. Learn about what ovarian reserve is, why these tests are done, and what to expect.
Are you or your partner finding it difficult to fall pregnant? Has your doctor proposed ovarian reserve testing? This article explains what ovarian reserve is, why these tests are done, and what to expect. Ovarian reserve tests are simple procedures that can tell a lot about reproductive potential.
Ovarian reserve testing and fertility
Ovarian reserve testing is a way for a doctor to estimate the quantity and quality of eggs (oocytes) you have in your ovaries (known as your ovarian reserve) and assess your fertility potential. These tests can be done in various ways, but ultimately, it helps to determine:
- The number and quality of eggs in your ovaries
- Why you may be experiencing issues with ovulation
- Why you’re having difficulty falling pregnant, especially if you are over 35 years old and have been unable to conceive during 6–12 months of having unprotected sex
- If you have any underlying and undiagnosed conditions
What is ovarian reserve? From maximum capacity to empty house
When you are forming in your mother’s body (embryogenesis), the process of making your eggs (oocytes) has already started. During this time, the eggs are in a very immature state known as germ cells. When you are about 20 weeks old in your mother’s uterus, you have approximately 6–7 million germ cells. These germ cells divide into individual cells and become known as primordial follicles, which is the earliest stage of an oocyte. By the time you are born, you have your lifetime supply of oocytes. At this time, your egg supply has already decreased to about 1–2 million follicles. This decline continues into puberty right through to menopause.
Having a good and healthy supply of eggs when you start puberty and throughout your adult life until you reach the menopause means you will have a good chance of falling pregnant naturally. However, several diseases, genetics, and environmental factors can jeopardise your natural ovarian reserve and cause early decline in eggs, disrupt egg production or influence sex hormones that control ovulation. This can all impact on your fertility chances.
What we don’t know is why some women experience a quicker decline of egg supply than others, and why there is a large variation in the amount of oocytes each woman has when they are born. Tests of ovarian reserve can help delve into the answers of these questions.
Why you might have reduced ovarian reserve?
Scientists know that certain diseases, genetics, and environmental factors can influence ovarian reserve:
Genetic or chromosomal factors: conditions, such as Turner’s syndrome, characteristically trigger a dramatic reduction in oocyte numbers early in life. Some women with Turner’s syndrome can go into menopause even before puberty. Other genetic or chromosomal conditions that can affect ovarian reserve include Fragile X syndrome (mutation in the FMR1gene) and Triple X syndrome (also known as trisomy X).
Medicated therapy: it is known that chemotherapy and radiotherapy can diminish a woman’s ovarian reserve. If a woman goes through these medical treatments, they will be at risk of a low ovarian reserve.
BRCA1 and 2 gene mutations: a combination of the above two factors, women with breast cancers related to the BRCA1or 2 gene mutations have also been linked to diminished ovarian reserve. One study found that BRCA1 patients, who underwent fertility preservation (oocyte storage) before chemotherapy, had a higher risk of primary ovarian insufficiency (POI) and a lower number of mature eggs suitable for cryopreservation. The exact way that these mutations impact ovarian reserve is unknown.
Early menopause or POI: menopause is the natural decline of oocytes and the arrest of menstrual periods. It usually occurs in women over the age of 45, with the average age being 51 years. Early menopause is classed as women going through the menopause between the age of 40–45 years. However, there are women experiencing infertility and menopausal-like symptoms earlier than 40 years, defined as primary ovarian insufficiency (POI). This is a condition where oocyte quantity and quality are significantly reduced. Women with POI find it difficult to conceive naturally due to irregular ovulation and hormonal imbalances. As mentioned above, POI can be seen in women with BRCA1 or 2 mutations, but there are also other causes.
Surgery: certain forms of pelvic surgery could cause damage or even destroy ovarian tissue and diminish ovarian reserve. Such surgeries could include surgical laparoscopy for treating endometriosis or removing ovarian cysts or uterine fibroids, as well as surgical removal of an ovary (oophorectomy).
Polycystic ovary syndrome (PCOS): PCOS is a common hormonal condition that can cause irregular periods, infertility and other health problems. It is characterised by a dysfunction of ovulation (anovulation), signs of excess androgen, and multiple ovarian cysts (confirmed by >10 follicles per ovary), however, these follicles don’t reach maturation and ovulation, thus remain in the ovary. An ovarian reserve test may be performed to help diagnose the condition.
Autoimmune disorders: disorders, such as thyroiditis (Hashimoto’s disorder) and systemic lupus, can trigger diminished ovarian reserve. One systematic review found that women with systemic lupus erythematosus had reduced levels of anti-Müllerian hormone (AMH), which is a hormone that helps in egg development, if low it indicates a poor ovarian reserve. Additionally, the treatment for the condition can further damage ovarian reserve. In another systematic review, reproductive aged women with Hashimoto’s thyroiditis had reduced AMH and a higher risk of diminished ovarian reserve.
Environmental factors: exposure to certain chemical in the environment, such as pesticides and endocrine disruptors, have been associated with triggering a decline in ovarian reserve. Some research has suggested that women who do shift work or have physically demanding jobs have fewer oocytes on retrieval when undergoing controlled ovarian hyperstimulation, which is a hormone treatment.
What’s involved in ovarian reserve testing?
There is no ideal test to assess ovarian reserve. So, a doctor may carry out one or a combination of the tests mentioned below to determine ovarian reserve. Firstly, they consist of blood tests to measure several hormone levels as markers of ovarian function, and if necessary followed by imaging (vaginal ultrasound). Each are relatively painless and minimally invasive.
- Measurement of hormones: AMH is produced by the developing oocytes, and high levels of AMH indicate a good quantity of oocytes. Its levels are considered a good indicator of ovarian reserve, as it does not fluctuate during the menstrual cycle. In fact, 51% of 796 fertility centres worldwide consider an AMH test as the best measurement of ovarian reserve.
Follicle-stimulating hormone (FSH) is also used to determine ovarian reserve. However, only 6% of centres in the above study indicated that FSH levels were considered a good indicator of ovarian reserve. FSH drives the maturation of oocytes, but it fluctuates during the cycle. For this reason, the blood test to analyse FSH is usually done on the third day of a woman’s cycle. Some doctors may also test for estradiol (a form of estrogen) levels and inhibin B (a hormone also released by oocytes). - Transvaginal ultrasound: This is an internal ultrasound that allows the visualisation of the ovaries from the cervix. It allows the doctor to perform an antral follicle count (AFC), which involves the doctor counting the number of small, fluid-filled sacs (also known as antral follicles) visible in both ovaries. This gives the doctor a good indication of the ovarian reserve and a woman’s fertility potential.
A count of 8–10 is considered normal. In addition, the ovarian volume may be calculated, which usually remains stable until menopausal years where it starts to reduce in volume, hence if a doctor detects a low ovarian volume it could indicate a low ovarian reserve.
Additionally, some tests maybe carried out to determine how your ovaries will respond to fertility drugs that stimulate follicle growth and ovulation, for example:
- Clomiphene Citrate Challenge Test (CCCT): This involves measuring a woman's FSH levels on day three of her menstrual cycle, then again on day 10 after taking clomiphene citrate from the fifth day of the cycle. A high FSH level on day 10 is considered a predictor of poor response to ovarian stimulation. This test is useful if a woman is being considered for in vitro fertilisation (IVF) treatment, because clomiphene citrate stimulates the ovaries to produce eggs.
If when performing a CCCT, the drug is unable to stimulate the ovaries to produce enough eggs for retrieval, then it may not be the best route to take for that woman. However, some fertility specialists believe that a CCCT is not a great predictor for IVF outcome, and hormonal (specifically AMH levels) and AFC are more accurate methods to predict ovarian reserve and the likelihood a woman will respond well to fertility drugs. - There are also exogenous FSH tests and gonadotropin-releasing hormone (GnRH) agonist stimulation test that are often used to check how your ovaries respond to fertility drugs and your potential for IVF treatment. A 2005 systematic review gives a thorough view on ovarian reserve tests and IVF outcomes.
What happens after an ovarian reserve test?
Your doctor will perform one or a combination of the tests mentioned. By considering these test results along with your age, fertility history and medical history (including any family history of low ovarian reserve or genetic conditions), they will be able to offer a good indication of your ovarian reserve and your fertility potential. They can also inform you of any conditions they may have detected through the examination. With this information, they will recommend treatment options depending on your conditions, symptoms or desire to fall pregnant.
Takeaway
The various ovarian reserve tests available are relatively painless and can offer a good indication of your ovarian reserve and fertility potential by determining the number and quality of eggs left in your ovaries. AMH levels and AFC are the main tests that can reveal a lot about how your ovaries are functioning. If your ovarian reserve is found to be low, it may indicate a decreased likelihood of conceiving naturally or successfully undergoing fertility treatments, such as IVF. But, if your ovarian reserve is found to be normal or high, it can offer reassurance and help with family planning decisions.
Your dedicated team of healthcare professionals at Cada can talk to you about ovarian reserve tests and determine if you are in need of one. Reserve your spot for a free consultation today.
