Ovulation Factors as a Cause of Infertility
As women age, their ovaries and the immature eggs contained therein age as well. Unlike men who produce new sperm on a regular basis, women are born with all the eggs they'll ever have. Their eggs may become damaged from years of exposure to hazards such as chemicals or radiation.
Too little estrogen also can cause infertility. As a woman ages and nears menopause, the amount of estrogen produced drops gradually. With less estrogen, the ovaries may not produce an egg each month. The result is fewer babies as a woman ages. Another cause for low estrogen levels is too little body fat. Women who exercise too much or diet excessively— sometimes due to eating disorders—may not produce enough estrogen for ovulation to occur.
Other women with ovulatory problems have sufficient supplies of estrogen but lack other hormones, such as FSH, LH, and prolactin, that affect other aspects of the cycle.
Certain kinds of birth control continue to reduce ovulation even after they are no longer used. For example, some women who take birth control pills find that it takes them a few months to begin ovulat¬ing again once they've stopped taking the pill. After 2-3 years off the pill, however, their rates of ovulation are the same as for other women who use barrier contraception. Contraceptive implants that contain hormones offer a rapid return of fertility. On the other hand, contraceptive injections of hormones may sub¬stantially delay the return of fertility. It can take anywhere from 4 to more than 30 months for fertility to return.
Tubal and Peritoneal Factors as a cause of Infertility
Conditions affecting the fallopian tubes or the peritoneum sometimes cause infertility. The peritoneum is a strong sac that lines the inside of the abdomen. It forms a sort of bag that contains the digestive organs and runs alongside the fallopian tubes.
Scarring or blockage in the tubes may cause infertility. One of the most common causes of damaged tubes is infections. When STDs are untreated, they can worsen and move up the uterus into the tubes. This is pelvic inflammatory disease, a major cause of blocked tubes. Use of an intrauterine device increases the risk of infection, especially in young women with several sexual partners. Some researchers say that smoking cigarettes changes the lining of the fallopian tubes, inflaming them and making them less hospitable to conception.
When tubes are damaged, an ectopic pregnancy is more likely if conception occurs. In an ectopic pregnancy, the egg is fertilized as in a normal pregnancy but it does not implant in the uterus. Instead, often because the fallopian tubes are damaged, it implants in the tube or somewhere in the peritoneum and begins to grow there. Because it can burst the tube, ectopic pregnancy can be life threatening. If you have a history of pelvic infections, your chances of ectopic pregnancy are four times greater than normal.
Other problems include adhesions, in which nearby organs or tissues bind themselves together. An adhesion that causes another organ to pull on a fallopian tube may move the tube away from the ovary. This prevents the tube from catching the egg when it is released. Adhesions may be caused by infection, previous surgery on the pelvic organs, or endometriosis.
The role of endometriosis in infertility is the subject of great debate among doctors. In endometriosis, tissue like that lining the uterus moves to other places in the abdomen where it begins growing in response to hormones, just as the endometrium does. Such growth can cause pain and inflammation. Up to one-third of infertile women are found to have endometriosis. We do not know if this is just a coincidence or if the endometriosis helps cause the infertility. Severe or extensive endometriosis can cause adhesions. Severe disease is definitely thought to be linked to infertility.
Cervical and Uterine Factors as a cause of Infertility
The cervix is the narrow neck that forms the opening of the uterus to the vagina. It produces mucus that either helps or hinders the movement of sperm depending on where a woman is in her menstrual cycle. As a woman nears ovulation, mucus thins and becomes slippery and stretchy to help move the sperm through the cervix. The mucus looks much like raw egg white. If the mucus is thick or scanty instead, it is much more difficult for the sperm to move. High levels of nicotine have been found in the cervical mucus of women who smoke. Nicotine can be toxic to sperm.
Surgery on the cervix may also interfere with fertility. Some types of operations, such as conization (removing a wedge of tissue from the cervix), may result in scarring or little to no mucus production.
Other Factors of Uterus as cause of Infertility
The uterus may be affected by infections or adhesions. An infection of the lining of the uterus, endometritis, can be caused by STDs such as gonorrhea. Tuberculosis also can cause endometritis. Overgrowth of the uterine lining, called endometrial hyperplasia, or endometrial cancer can cause infertility as well.
If a woman has had the lining of her uterus scraped by D&C, or dilation and curettage after a pregnancy or for abnormal bleeding, the lining may not grow back properly. Adhesions may form, or the lining may be thin; either condition can contribute to infertility. The condition is known as Asherman’s Syndrome.
Growths in the uterus, such as fibroids, have been studied as possible causes of infertility. Although they may play a small role, if any in infertility, a doctor may remove them if no other cause for infertility is found.
An abnormally shaped uterus, such as one with a thin wall (septum) running down its middle, also known as septate uterus, can affect a woman's ability to have a child. Affected women are born with these defects that cause miscarriage (loss of the baby before it is ready to be born) rather than inability to conceive.
Antibodies against Sperm prevent Fertilization
Some women and men produce antibodies against sperm. When the immune system malfunctions, it sees the sperm as a foreign threat and produces anti¬bodies to fight them. The antibodies affect the ability of the sperm to move freely.
Unexplained Infertility
Sometimes a reason cannot be found for a couple's infertility. Even without knowing a cause, however, certain steps can be taken to increase the chance of conceiving. Some measures a couple can take them¬selves. Each month, approximately 3 percent of cou¬ples with unexplained infertility conceive on their own.
Showing posts with label ovulation. Show all posts
Showing posts with label ovulation. Show all posts
Wednesday, March 18, 2009
What is ovulation and how one gets pregnant?
To achieve pregnancy a series of complicated events occurs, which otherwise happens so simply! It is essential to know the normal process so that we can understand the reason; when there is difficulty of getting pregnant.
Ovulation and menstruation – What actually happens?
A woman is born with a lifetime supply of immature eggs in her ovaries. Each month, one matures and is released in a process called ovulation. Ovulation is an important part of the menstrual cycle. In a typical 28-day cycle, a woman's menstrual period begins on day 1. On day 14, ovulation occurs. On day 28, if the egg has not become fertilized, the menstrual cycle begins again with another period.
For ovulation to happen, different parts of the body must all work together. The brain and the ovaries both play roles in this coordination. The ovaries are the two almond-shaped glands sitting within reach of the fallopian tubes. Ovaries produce the eggs as well as the essential sex hormones needed for menstruation and pregnancy.
Just before ovulation, the hypothalamus and pituitary glands in the brain signal the body to start producing hormones. Follicle-stimulating hormone (FSH) prompts fluid-filled chambers in the ovary called follicles to begin growing. In each follicle a single ovum starts growing. Leutinizing hormone (LH) triggers the follicle to rupture when it is matured. In each cycle one ovum is usually released. Women ovulate about 14 days before their next menstrual period would be expected—day 14 on a 28-day cycle. Ovulation occurs within about a day after the surge in LH.
Both FSH and LH play additional roles in the menstrual cycle. They instruct the ovaries to produce estrogen and progesterone, hormones that help ovulation to occur and the uterus to prepare for pregnancy. The uterus is a hollow organ, shaped like a pear and only about three inches long in a non pregnant woman. Its lining, the endometrium, is richly supplied with blood vessels. The endometrium continually renews itself, building up in response to messages sent by estrogen and progesterone.
The Luteinizing Process The menstrual cycle consists of a complex series of events that interact to stimulate ovulation, prepare the uterine lining for a pregnancy, and cause the uterine lining to be shed if pregnancy does not occur. Two glands in the brain, the hypothalamus and the pituitary, send follicle-stimulating hormone (FSH) and luteinizing hormone (LH) to the ovary just before ovulation to stimulate the development of a follicle and its release of an egg into a fallopian tube (ovulation). Follicles are the structures inside the ovary that produce the eggs to be fertilized and that release the hormone estrogen, which stimulates the lining of the uterus to thicken in preparation for pregnancy. After releasing the egg, the empty follicle, called the corpus-luteum, begins producing progesterone. This hormone continues to stimulate the uterine lining to grow and thicken. If the egg is not fertilized, a sudden drop in estrogen and progesterone triggers the uterus to shed its lining and menstruation begins. This marks the start of the next cycle
What actually happens when ovum is fertilized?
For fertilization to occur, healthy sperm must be deposited in a woman's vagina, preferably near the cervix, just about the time of ovulation. Each sperm is about 1/ 1000 inch long; its whip like tail swims up through the cervix, into the uterus, and into the fallopian tubes. Only one sperm is allowed fertilize an egg. Though millions of sperm may start their journey towards the solitary ovum, only a few hundred stay alive during the trip and one fortunate sperm ultimately fertilize the egg.
An egg, which is released during ovulation is usually picked up by the fallopian tube. Women have two fallopian tubes, each about 4 inches long. They are located just above the ovaries and have featherlike fingers called fimbria at their terminals near the ovaries. The fimbria and inner lining of the tubes are lined with cilia, which are like millions of active tiny hairs. These hairs shift the egg from the ovary inside the tubes by suction and cilliary action. An egg is fertilizable for only about 12-72 hours after its release.
The fallopian tubes have smooth tiny musculature throughout their lengths. In the middle, they help by contracting so that the sperm and egg move closer with each other and fertilization happens. At the end nearer the uterus, they are narrow to keep eggs from being released into the uterus too soon.
When sperm are present, they gather around the egg. They discharge enzymes from their heads to help make a hole in the egg to allow penetration. Once one sperm enters the egg, a chemical reaction ensues that pre¬vents other sperm from entering.
In the first half of a woman's menstrual cycle, estrogen makes the endometrial lining begin to thicken with a nutrient rich bedding in case pregnancy should occur. Progesterone then takes over. It is produced mainly in the second half of the cycle by a temporary organ called the corpus luteum. The corpus luteum is formed in the ovary from the follicle that released its egg. Progesterone causes the lining of the uterus to thicken even more. Estrogen and progesterone both play roles in ovulation as well.
If the egg is not fertilized, it dissolves and is absorbed by the body. Then hormone levels drop and the endometrium disintegrates without the hormonal nourishment. This shedding is the monthly menstrual period. The first day of a woman's period is the point at which her hormone levels are at their lowest.
How fertilized ovum is implanted in the uterus?
Inside the fertilized egg, cells begin to divide. If all goes well, the fertilized egg then journeys from the fallopian tube to the uterus where it implants itself in the spongy lining of the uterus. There it grows and develops into an embryo (weeks 2-8), then a fetus for the rest of the pregnancy, and 9 months later, a baby.
Numerous structural and hormonal factors play a part in fertility. What may look like the simplest of human activities—conceiving a baby—can become a miraculous chain of events, especially to a couple having problems getting pregnant.
Basic criteria of a fertile couple
Seven elements are essential to fertility:
1. A woman's ovaries must produce healthy eggs that are released regularly.
2. A man's testicles must be capable of producing healthy sperm that can reach the egg and then penetrate it.
3. During intercourse, the man's semen that contains his sperm has to be deposited at or at least close to the cervix. This puts the sperm in the best position to reach the egg.
4. There has to be a clear passage through the fallopian tube from the ovary to the uterus. This passage is used by both the egg moving down and the sperm moving up. Any obstruction in the fallopian tube interrupts the process of fertilization.
5. The man's sperm have to be able to move freely through the cervix. Any physical or chemical barrier can cause problems.
6. The ovum has 12 to 72 hours of life in which it can be fertilized. The sperm have up to 5 days in which they can fertilize an egg. Timing is critical.
7. Once the egg is fertilized, it has to find a suitable site for implantation in the lining of the uterus.
Ovulation and menstruation – What actually happens?
A woman is born with a lifetime supply of immature eggs in her ovaries. Each month, one matures and is released in a process called ovulation. Ovulation is an important part of the menstrual cycle. In a typical 28-day cycle, a woman's menstrual period begins on day 1. On day 14, ovulation occurs. On day 28, if the egg has not become fertilized, the menstrual cycle begins again with another period.
For ovulation to happen, different parts of the body must all work together. The brain and the ovaries both play roles in this coordination. The ovaries are the two almond-shaped glands sitting within reach of the fallopian tubes. Ovaries produce the eggs as well as the essential sex hormones needed for menstruation and pregnancy.
Just before ovulation, the hypothalamus and pituitary glands in the brain signal the body to start producing hormones. Follicle-stimulating hormone (FSH) prompts fluid-filled chambers in the ovary called follicles to begin growing. In each follicle a single ovum starts growing. Leutinizing hormone (LH) triggers the follicle to rupture when it is matured. In each cycle one ovum is usually released. Women ovulate about 14 days before their next menstrual period would be expected—day 14 on a 28-day cycle. Ovulation occurs within about a day after the surge in LH.
Both FSH and LH play additional roles in the menstrual cycle. They instruct the ovaries to produce estrogen and progesterone, hormones that help ovulation to occur and the uterus to prepare for pregnancy. The uterus is a hollow organ, shaped like a pear and only about three inches long in a non pregnant woman. Its lining, the endometrium, is richly supplied with blood vessels. The endometrium continually renews itself, building up in response to messages sent by estrogen and progesterone.
The Luteinizing Process The menstrual cycle consists of a complex series of events that interact to stimulate ovulation, prepare the uterine lining for a pregnancy, and cause the uterine lining to be shed if pregnancy does not occur. Two glands in the brain, the hypothalamus and the pituitary, send follicle-stimulating hormone (FSH) and luteinizing hormone (LH) to the ovary just before ovulation to stimulate the development of a follicle and its release of an egg into a fallopian tube (ovulation). Follicles are the structures inside the ovary that produce the eggs to be fertilized and that release the hormone estrogen, which stimulates the lining of the uterus to thicken in preparation for pregnancy. After releasing the egg, the empty follicle, called the corpus-luteum, begins producing progesterone. This hormone continues to stimulate the uterine lining to grow and thicken. If the egg is not fertilized, a sudden drop in estrogen and progesterone triggers the uterus to shed its lining and menstruation begins. This marks the start of the next cycle
What actually happens when ovum is fertilized?
For fertilization to occur, healthy sperm must be deposited in a woman's vagina, preferably near the cervix, just about the time of ovulation. Each sperm is about 1/ 1000 inch long; its whip like tail swims up through the cervix, into the uterus, and into the fallopian tubes. Only one sperm is allowed fertilize an egg. Though millions of sperm may start their journey towards the solitary ovum, only a few hundred stay alive during the trip and one fortunate sperm ultimately fertilize the egg.
An egg, which is released during ovulation is usually picked up by the fallopian tube. Women have two fallopian tubes, each about 4 inches long. They are located just above the ovaries and have featherlike fingers called fimbria at their terminals near the ovaries. The fimbria and inner lining of the tubes are lined with cilia, which are like millions of active tiny hairs. These hairs shift the egg from the ovary inside the tubes by suction and cilliary action. An egg is fertilizable for only about 12-72 hours after its release.
The fallopian tubes have smooth tiny musculature throughout their lengths. In the middle, they help by contracting so that the sperm and egg move closer with each other and fertilization happens. At the end nearer the uterus, they are narrow to keep eggs from being released into the uterus too soon.
When sperm are present, they gather around the egg. They discharge enzymes from their heads to help make a hole in the egg to allow penetration. Once one sperm enters the egg, a chemical reaction ensues that pre¬vents other sperm from entering.
In the first half of a woman's menstrual cycle, estrogen makes the endometrial lining begin to thicken with a nutrient rich bedding in case pregnancy should occur. Progesterone then takes over. It is produced mainly in the second half of the cycle by a temporary organ called the corpus luteum. The corpus luteum is formed in the ovary from the follicle that released its egg. Progesterone causes the lining of the uterus to thicken even more. Estrogen and progesterone both play roles in ovulation as well.
If the egg is not fertilized, it dissolves and is absorbed by the body. Then hormone levels drop and the endometrium disintegrates without the hormonal nourishment. This shedding is the monthly menstrual period. The first day of a woman's period is the point at which her hormone levels are at their lowest.
How fertilized ovum is implanted in the uterus?
Inside the fertilized egg, cells begin to divide. If all goes well, the fertilized egg then journeys from the fallopian tube to the uterus where it implants itself in the spongy lining of the uterus. There it grows and develops into an embryo (weeks 2-8), then a fetus for the rest of the pregnancy, and 9 months later, a baby.
Numerous structural and hormonal factors play a part in fertility. What may look like the simplest of human activities—conceiving a baby—can become a miraculous chain of events, especially to a couple having problems getting pregnant.
Basic criteria of a fertile couple
Seven elements are essential to fertility:
1. A woman's ovaries must produce healthy eggs that are released regularly.
2. A man's testicles must be capable of producing healthy sperm that can reach the egg and then penetrate it.
3. During intercourse, the man's semen that contains his sperm has to be deposited at or at least close to the cervix. This puts the sperm in the best position to reach the egg.
4. There has to be a clear passage through the fallopian tube from the ovary to the uterus. This passage is used by both the egg moving down and the sperm moving up. Any obstruction in the fallopian tube interrupts the process of fertilization.
5. The man's sperm have to be able to move freely through the cervix. Any physical or chemical barrier can cause problems.
6. The ovum has 12 to 72 hours of life in which it can be fertilized. The sperm have up to 5 days in which they can fertilize an egg. Timing is critical.
7. Once the egg is fertilized, it has to find a suitable site for implantation in the lining of the uterus.
Monday, February 23, 2009
Predict ovulation in infertile couples by Ultrasonography
What the sonologist sees to predict ovulation?
A small echogenic mass that is thought to represent the cumulus oophorus may sometimes be noted projecting into the follicle. Visualization of the cumulus oophorus has been reported in 80 percent of follicles greater than 17 mm in diameter. Ovulation is reported to be within 36 hours of seeing the cumulus. After the LH surge, the theca tissue becomes hypervascular and edematous and the granulosa cell layer begins to separate from the theca layer. This is appreciated sonographically as a line of decreased reflectivity around the follicle. Within 6 to 10 hours before ovulation, separation and folding of the granu¬losa cell layer produces a crenation or irregularity of the lining of the follicle. This has also been suggested as sign of impending ovulation. Unfortunately, despite the fact that there are a number of sonographic signs that have been described to precede ovulation, there is currently no sonography sign that predicts exactly when ovulation will occur, the signs only give evidence that the time of ovulation is nearing. The mean peak diameter before ovulation reported by Kerin et al was 23.6 + 0.4 mm. However, there are considerable differences in the same.
Hence, the potential signs of impending ovulation are:
• Presence of a dominant follicle (usually more than 16 to 18 mm)
• Anechoic area, double contour, around the follicle (possible ovulation within 24 hrs)
• Separation and folding of the follicle lining (ovulation within 6 to 10 hrs)
• Thickened proliferative endometrium (described later)
How USG confirms that there is ovulation?
Sonography does appear to be very reliable in confirming ovulation once ovulation has occurred. Disappearance of the follicle is noted in 91 percent of cases after ovulation and a decrease in follicle size occurs in another 9 percent. Other signs suggesting that ovulation has occurred are the appearance of cul-de-sac fluid, particularly when it was not present in a previous scan, or the development of intratollicular echoes suggesting the formation of a hemorrhagic corpus luteum.
How anovulation is diagnosed by sonography?
In an anovulatory cycle, ultrasound imaging of the ovaries will reveal either a lack of any follicular development, particularly in the hypogonadotropic hypogonadal patient WHO type I or a few non ovulatory (less than 11 mm) follicles. A dominant follicle larger than 16 mm in diameter will not develop. A cyst may also be associated with anovulation. Anovulation with PCOD will often have enlarged ovaries greater than 8 cm3 in volume with multiple small subcapsular follicles less than 10 mm in diameter. However, normal sized ovaries do not rule out PCOD. Anovulation can be diagnosed when serial scans do not show development of a follicle. A mature corpus luteum is noted sonographically in about 50 percent of patients after ovulation. If pregnancy does not occur the corpus luteum generally degenerates and disappears just before menstruation. Corpus luteum cysts may be 4 to 6 cms in diamter and occasionally even large but are more commonly 2.5 to 3 cms in diameter. They may persist for 4 to 12 weeks and may be responsible for suppressing normal follicular development until they resolve.
This article is also published in India Study Channel
A small echogenic mass that is thought to represent the cumulus oophorus may sometimes be noted projecting into the follicle. Visualization of the cumulus oophorus has been reported in 80 percent of follicles greater than 17 mm in diameter. Ovulation is reported to be within 36 hours of seeing the cumulus. After the LH surge, the theca tissue becomes hypervascular and edematous and the granulosa cell layer begins to separate from the theca layer. This is appreciated sonographically as a line of decreased reflectivity around the follicle. Within 6 to 10 hours before ovulation, separation and folding of the granu¬losa cell layer produces a crenation or irregularity of the lining of the follicle. This has also been suggested as sign of impending ovulation. Unfortunately, despite the fact that there are a number of sonographic signs that have been described to precede ovulation, there is currently no sonography sign that predicts exactly when ovulation will occur, the signs only give evidence that the time of ovulation is nearing. The mean peak diameter before ovulation reported by Kerin et al was 23.6 + 0.4 mm. However, there are considerable differences in the same.
Hence, the potential signs of impending ovulation are:
• Presence of a dominant follicle (usually more than 16 to 18 mm)
• Anechoic area, double contour, around the follicle (possible ovulation within 24 hrs)
• Separation and folding of the follicle lining (ovulation within 6 to 10 hrs)
• Thickened proliferative endometrium (described later)
How USG confirms that there is ovulation?
Sonography does appear to be very reliable in confirming ovulation once ovulation has occurred. Disappearance of the follicle is noted in 91 percent of cases after ovulation and a decrease in follicle size occurs in another 9 percent. Other signs suggesting that ovulation has occurred are the appearance of cul-de-sac fluid, particularly when it was not present in a previous scan, or the development of intratollicular echoes suggesting the formation of a hemorrhagic corpus luteum.
How anovulation is diagnosed by sonography?
In an anovulatory cycle, ultrasound imaging of the ovaries will reveal either a lack of any follicular development, particularly in the hypogonadotropic hypogonadal patient WHO type I or a few non ovulatory (less than 11 mm) follicles. A dominant follicle larger than 16 mm in diameter will not develop. A cyst may also be associated with anovulation. Anovulation with PCOD will often have enlarged ovaries greater than 8 cm3 in volume with multiple small subcapsular follicles less than 10 mm in diameter. However, normal sized ovaries do not rule out PCOD. Anovulation can be diagnosed when serial scans do not show development of a follicle. A mature corpus luteum is noted sonographically in about 50 percent of patients after ovulation. If pregnancy does not occur the corpus luteum generally degenerates and disappears just before menstruation. Corpus luteum cysts may be 4 to 6 cms in diamter and occasionally even large but are more commonly 2.5 to 3 cms in diameter. They may persist for 4 to 12 weeks and may be responsible for suppressing normal follicular development until they resolve.
This article is also published in India Study Channel
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