Ovarian reserve
Encyclopedia
Ovarian reserve is a term that is used to determine the capacity of the ovary
to provide eggs
that are capable of fertilization resulting in a healthy and successful pregnancy
. While there is no known method for assessing the ovarian reserve of individual women, indirect determination of ovarian reserve is important in the treatment of infertility
.
The ovary is generally thought of as an egg bank from which the woman draws during her reproductive life. The human ovary contains a population of primordial follicles. At 18–22 weeks post-conception, the female ovary
contains its peak number of follicles (about 300,000 in the average case, but individual peak populations range from 35,000 to 2.5 million). While each month one egg is released by ovulation the remaining follicles that were recruited towards maturation are lost by atresia
. Few if any oocytes are replenished during the reproductive years. Thus with advanced maternal age
the number of eggs that can be successfully recruited for a possible pregnancy declines. Attempts have been made to assess the number of potential useful oocytes in a noninvasive way.
The most commonly used test to assess this ovarian reserve is the day 3 FSH test. This blood test determines the level of FSH
on cycle day 3. Cycle day 3 is chosen because at this time the estrogen
level is expected to be low, a critical feature, as FSH levels are subject to a negative feedback
.
Thus any determination of FSH needs to include the corresponding estradiol
level to indicate that the FSH level was drawn, when the estrogen level was low. In a patient with infrequent menstruation, an FSH level and estrogen level could be measured at random and is valid if the estrogen level is low. Generally FSH levels are expected to be below 10 miu
/ml in women with reproductive potential (levels of 10-15 miu/ml are considered borderline), however the exact numbers returned will depend on the type of assay used in a particular laboratory.
Although FSH and more recently Inhibin B have been shown to have some correlation with ovarian reserve, it is now well established that Anti-Mullerian Hormone or AMH is more useful biochemical test. High levels however can be present in women with Polycystic Ovarian Syndrome which compromises female fertility and therefore a combination of AMH and a transvaginal ultrasound to count the number of antral follicles is probably the best way to assess ovarian reserve and future fertility. This combination is sometimes referred to as the Biological Body Clock Test.
A clomiphene challenge test is a variation on this approach.
Another approach is to examine the ovaries by gynecologic ultrasonography
and to determine their size as ovaries depleted of eggs tend to be smaller and to examine the number of antral follicles visible by sonography.
Women with poor ovarian reserve are unlikely to conceive with infertility therapy. Also see poor ovarian reserve
and Follicle-stimulating hormone
for treatment options.
Ovary
The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in anatomically female individuals are analogous to testes in anatomically male individuals, in that they are both gonads and endocrine glands.-Human anatomy:Ovaries...
to provide eggs
Ovum
An ovum is a haploid female reproductive cell or gamete. Both animals and embryophytes have ova. The term ovule is used for the young ovum of an animal, as well as the plant structure that carries the female gametophyte and egg cell and develops into a seed after fertilization...
that are capable of fertilization resulting in a healthy and successful pregnancy
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
. While there is no known method for assessing the ovarian reserve of individual women, indirect determination of ovarian reserve is important in the treatment of infertility
Infertility
Infertility primarily refers to the biological inability of a person to contribute to conception. Infertility may also refer to the state of a woman who is unable to carry a pregnancy to full term...
.
The ovary is generally thought of as an egg bank from which the woman draws during her reproductive life. The human ovary contains a population of primordial follicles. At 18–22 weeks post-conception, the female ovary
Ovary
The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in anatomically female individuals are analogous to testes in anatomically male individuals, in that they are both gonads and endocrine glands.-Human anatomy:Ovaries...
contains its peak number of follicles (about 300,000 in the average case, but individual peak populations range from 35,000 to 2.5 million). While each month one egg is released by ovulation the remaining follicles that were recruited towards maturation are lost by atresia
Ovarian follicle atresia
Ovarian follicle atresia is the periodic process in which immature ovarian follicles degenerate and are subsequently re-absorbed during the follicular phase of the menstrual cycle. Typically around 20 follicles mature each month and only a single follicle is ovulated. The rest undergo atresia...
. Few if any oocytes are replenished during the reproductive years. Thus with advanced maternal age
Advanced maternal age
Advanced maternal age is defined as an increase in the age at which women give birth to their first child, is now a widespread, and indeed near universal, phenomenon across the OECD countries....
the number of eggs that can be successfully recruited for a possible pregnancy declines. Attempts have been made to assess the number of potential useful oocytes in a noninvasive way.
The most commonly used test to assess this ovarian reserve is the day 3 FSH test. This blood test determines the level of FSH
Follicle-stimulating hormone
Follicle-stimulating hormone is a hormone found in humans and other animals. It is synthesized and secreted by gonadotrophs of the anterior pituitary gland. FSH regulates the development, growth, pubertal maturation, and reproductive processes of the body. FSH and Luteinizing hormone act...
on cycle day 3. Cycle day 3 is chosen because at this time the estrogen
Estrogen
Estrogens , oestrogens , or œstrogens, are a group of compounds named for their importance in the estrous cycle of humans and other animals. They are the primary female sex hormones. Natural estrogens are steroid hormones, while some synthetic ones are non-steroidal...
level is expected to be low, a critical feature, as FSH levels are subject to a negative feedback
Negative feedback
Negative feedback occurs when the output of a system acts to oppose changes to the input of the system, with the result that the changes are attenuated. If the overall feedback of the system is negative, then the system will tend to be stable.- Overview :...
.
Thus any determination of FSH needs to include the corresponding estradiol
Estradiol
Estradiol is a sex hormone. Estradiol is abbreviated E2 as it has 2 hydroxyl groups in its molecular structure. Estrone has 1 and estriol has 3 . Estradiol is about 10 times as potent as estrone and about 80 times as potent as estriol in its estrogenic effect...
level to indicate that the FSH level was drawn, when the estrogen level was low. In a patient with infrequent menstruation, an FSH level and estrogen level could be measured at random and is valid if the estrogen level is low. Generally FSH levels are expected to be below 10 miu
International unit
In pharmacology, the International Unit is a unit of measurement for the amount of a substance, based on biological activity or effect. It is abbreviated as IU, as UI , or as IE...
/ml in women with reproductive potential (levels of 10-15 miu/ml are considered borderline), however the exact numbers returned will depend on the type of assay used in a particular laboratory.
Although FSH and more recently Inhibin B have been shown to have some correlation with ovarian reserve, it is now well established that Anti-Mullerian Hormone or AMH is more useful biochemical test. High levels however can be present in women with Polycystic Ovarian Syndrome which compromises female fertility and therefore a combination of AMH and a transvaginal ultrasound to count the number of antral follicles is probably the best way to assess ovarian reserve and future fertility. This combination is sometimes referred to as the Biological Body Clock Test.
A clomiphene challenge test is a variation on this approach.
Another approach is to examine the ovaries by gynecologic ultrasonography
Gynecologic ultrasonography
Gynecologic ultrasonography or Gynecologic sonography refers to the application of medical ultrasonography to the female pelvic organs, specifically the uterus, the ovaries, the Fallopian tubes, as well as the bladder, the adnexa, the Pouch of Douglas, and any findings in the pelvis of relevance...
and to determine their size as ovaries depleted of eggs tend to be smaller and to examine the number of antral follicles visible by sonography.
Women with poor ovarian reserve are unlikely to conceive with infertility therapy. Also see poor ovarian reserve
Poor ovarian reserve
Poor ovarian reserve is a condition of low fertility characterized by 1): low numbers of remaining oocytes in the ovaries or 2) possibly impaired preantral oocyte development or recruitment...
and Follicle-stimulating hormone
Follicle-stimulating hormone
Follicle-stimulating hormone is a hormone found in humans and other animals. It is synthesized and secreted by gonadotrophs of the anterior pituitary gland. FSH regulates the development, growth, pubertal maturation, and reproductive processes of the body. FSH and Luteinizing hormone act...
for treatment options.