Anovulatory cycle
Encyclopedia
The anovulatory cycle is a menstrual cycle
characterized by varying degrees of menstrual intervals and the absence of ovulation
and a luteal phase
. In the absence of ovulation, there will be infertility
.
in the human
typically lasts 4 weeks (28 days, range 21-35 days) and consists of a follicular phase
, ovulation
, and a luteal phase
, followed by either menstruation
or pregnancy
, the anovulatory cycle has cycle lengths of varying degrees. In many circumstances, menstrual intervals are prolonged exceeding 35 days leading to oligomenorrhea
(cycle >35- 180 days interval), or even longer, amenorrhea. In other cases, menstruation may be fairly regular (eumenorrhea), or more frequent (intervals < 21 days), or there may be a loss of menstrual pattern (menorrhagia
, dysfunctional uterine bleeding
).
due to the demise of the corpus luteum
. It is thus a progesterone withdrawal bleeding. As there is no progesterone in the anovulatory cycle, bleeding is caused by the inability of estrogen
- that needs to be present to stimulate the endometrium
in the first place - to support a growing endometrium. Anovulatory bleeding is hence termed estrogen breakthrough bleeding.
With excessive or prolonged bleeding the diagnosis has to be made by a physician on a speedy basis. Other causes of gynecological bleeding need to be excluded, specifically bleeding related to pregnancy
, leiomyoma
, and cancer
of the cervix
or uterus
.
In patients who do not want to get pregnant anovulation can be managed with the use of cyclic progesterone
or progestin
supplementation or use of hormonal contraception
.
Menstrual cycle
The menstrual cycle is the scientific term for the physiological changes that can occur in fertile women for the purpose of sexual reproduction. This article focuses on the human menstrual cycle....
characterized by varying degrees of menstrual intervals and the absence of ovulation
Ovulation
Ovulation is the process in a female's menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum . Ovulation also occurs in the estrous cycle of other female mammals, which differs in many fundamental ways from the menstrual cycle...
and a luteal phase
Luteal phase
The luteal phase is the latter phase of the menstrual cycle or the estrous cycle . It begins with the formation of the corpus luteum and ends in either pregnancy or luteolysis...
. In the absence of ovulation, there will be 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...
.
Patterns
While the normal menstrual cycleMenstrual cycle
The menstrual cycle is the scientific term for the physiological changes that can occur in fertile women for the purpose of sexual reproduction. This article focuses on the human menstrual cycle....
in the human
Human
Humans are the only living species in the Homo genus...
typically lasts 4 weeks (28 days, range 21-35 days) and consists of a follicular phase
Follicular phase
The follicular phase is the phase of the estrous cycle, during which follicles in the ovary mature. It ends with ovulation. The main hormone controlling this stage is estradiol....
, ovulation
Ovulation
Ovulation is the process in a female's menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum . Ovulation also occurs in the estrous cycle of other female mammals, which differs in many fundamental ways from the menstrual cycle...
, and a luteal phase
Luteal phase
The luteal phase is the latter phase of the menstrual cycle or the estrous cycle . It begins with the formation of the corpus luteum and ends in either pregnancy or luteolysis...
, followed by either menstruation
Menstruation
Menstruation is the shedding of the uterine lining . It occurs on a regular basis in sexually reproductive-age females of certain mammal species. This article focuses on human menstruation.-Overview:...
or 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...
, the anovulatory cycle has cycle lengths of varying degrees. In many circumstances, menstrual intervals are prolonged exceeding 35 days leading to oligomenorrhea
Oligomenorrhea
Oligomenorrhea is infrequent menstruation. More strictly, it is menstrual periods occurring at intervals of greater than 35 days, with only four to nine periods in a year. Also, menstrual periods should have been regularly established previously before the development of infrequent flow...
(cycle >35- 180 days interval), or even longer, amenorrhea. In other cases, menstruation may be fairly regular (eumenorrhea), or more frequent (intervals < 21 days), or there may be a loss of menstrual pattern (menorrhagia
Menorrhagia
Menorrhagia is an abnormally heavy and prolonged menstrual period at regular intervals. Causes may be due to abnormal blood clotting, disruption of normal hormonal regulation of periods or disorders of the endometrial lining of the uterus...
, dysfunctional uterine bleeding
Dysfunctional uterine bleeding
Dysfunctional Uterine Bleeding is abnormal genital tract bleeding based in the uterus and found in the absence of demonstrable structural or organic pathology.usually due to hormonal disturbances....
).
Estrogen breakthrough bleeding
Normal menstrual bleeding in the ovulatory cycle is a result of a decline in progesteroneProgesterone
Progesterone also known as P4 is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species...
due to the demise of the corpus luteum
Corpus luteum
The corpus luteum is a temporary endocrine structure in mammals, involved in production of relatively high levels of progesterone and moderate levels of estradiol and inhibin A...
. It is thus a progesterone withdrawal bleeding. As there is no progesterone in the anovulatory cycle, bleeding is caused by the inability of 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...
- that needs to be present to stimulate the endometrium
Endometrium
-Function:The endometrium is the innermost glandular layer and functions as a lining for the uterus, preventing adhesions between the opposed walls of the myometrium, thereby maintaining the patency of the uterine cavity. During the menstrual cycle or estrous cycle, the endometrium grows to a...
in the first place - to support a growing endometrium. Anovulatory bleeding is hence termed estrogen breakthrough bleeding.
Diagnosis
A physician needs to investigate the cause of anovulation. Common causes are:- Polycystic ovary syndromePolycystic ovary syndromePolycystic ovary syndrome is one of the most common female endocrine disorders. PCOS is a complex, heterogeneous disorder of uncertain aetiology, but there is strong evidence that it can to a large degree be classified as a genetic disease....
- Hypothalamic dysfunction
- Perimenopause
- Ovulatory dysfunction
- ThyroidThyroidThe thyroid gland or simply, the thyroid , in vertebrate anatomy, is one of the largest endocrine glands. The thyroid gland is found in the neck, below the thyroid cartilage...
disorders - Hyperprolactinemia
With excessive or prolonged bleeding the diagnosis has to be made by a physician on a speedy basis. Other causes of gynecological bleeding need to be excluded, specifically bleeding related to 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...
, leiomyoma
Leiomyoma
A leiomyoma is a benign smooth muscle neoplasm that is not premalignant. They can occur in any organ, but the most common forms occur in the uterus, small bowel and the esophagus.- Etymology:* Greek:** λεῖος leios "smooth"...
, and cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
of the cervix
Cervix
The cervix is the lower, narrow portion of the uterus where it joins with the top end of the vagina. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall...
or uterus
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
.
Management
Women who don't ovulate and who want to get pregnant need a medical work-up to find out why they don't ovulate. Drugs are often given to induce ovulation, including oral medication such as clomiphene or injectable medications.In patients who do not want to get pregnant anovulation can be managed with the use of cyclic progesterone
Progesterone
Progesterone also known as P4 is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species...
or progestin
Progestin
A progestin is a synthetic progestogen that has progestinic effects similar to progesterone. The two most common uses of progestins are for hormonal contraception , and to prevent endometrial hyperplasia from unopposed estrogen in hormone replacement therapy...
supplementation or use of hormonal contraception
Hormonal contraception
Hormonal contraception refers to birth control methods that act on the endocrine system. Almost all methods are composed of steroid hormones, although in India one selective estrogen receptor modulator is marketed as a contraceptive. The original hormonal method—the combined oral contraceptive...
.