Irregular Periods in Women with Polycystic Ovary Syndrome

 

Absent or delayed periods are common symptoms in women with polycystic ovary syndrome. These women usually have less than eight periods each year. Absence of periods causes thickening of inner lining of uterus (endometrium). These women with thickened inner lining of uterus may have bleedings which are long lasting, heavy and including dark coagulum. The women with thickened inner lining of uterus have also an increased risk of developing cancer in the inner lining of uterus.

The menstrual cycle is the time from the first day of a woman’s period to the first day of her next period (For example; 30 day cycle). The beginning of a woman’s period in the end of a menstrual cycle generally accepted as a sign of ovulation.

For example; a woman ovulates about 12 times a year if she gets periods once a month, a woman ovulates about 6 times a year if she gets periods every two months, a woman ovulates about two times a year if she gets periods every six months. But, the beginning of a period or having regular periods may not be a sign of ovulation in some women with polycystic ovary syndrome. For this reason, ovulation should be determined in these women with regular monthly periods having symptoms such as excessive hair growth, acne, male type hair loss or obesity. Ultrasound scan or some hormone tests should be done to know whether these women are ovulating or not.

This picture demonstrates an ultrasound image of polycystic ovary. The red arrow in the picture shows fluid filled small sacs containing eggs which surrounds the increased amount of white central area (stroma) of the ovary.

 

Figure-1 (below) shows the changes in blood levels of some hormones called FSH (Follicle Stimulating Hormone), LH (Luteinizing Hormone), Estradiol, and Progesterone during a menstrual cycle with ovulation. The changes in the production of these hormones during a menstrual cycle leads to growth of small sac with an egg and results in ovulation. The yellow line in figure-1 (below) illustrates the changes in the amount of FSH in a menstrual cycle. FSH leads to growing of a sac which contains egg starting from the first day of a menstrual cycle. The blue line in figure-1 (below) demonstrates the changes in the amount of estradiol. At the same time with the growing a sac containing egg, estradiol leads to thickening of inner lining of uterus (endometrium). The green line in figure-1 (below) illustrates the changes in the amount of LH in a menstrual cycle. The wall of a growing sac with egg ruptures and egg is released from the ovary, 36 hours after the highest level of LH in the menstrual cycle. The release of an egg from the ovary is known as ovulation. Pregnancy can occur if an egg which is released from the ovary (ovulation) meets with a sperm. Otherwise, menstrual bleeding usually will begin about 14 days after ovulation if the egg does not meet with a sperm.

The red line in figure-1 (below) illustrates the changes in the amount of progesterone in a menstrual cycle. Progesterone reaches its highest level 7 days after ovulation in a menstrual cycle. Progesterone levels can be measured by a blood test to determine whether ovulation has occurred or not. Menstrual bleeding usually will begin about 7 days after the progesterone reaches its highest level in a menstrual cycle. The menstrual cycle shown in figure-1 (below) lasting 28 days ends when menstrual bleeding begins 7 days after the progesterone has reached its highest level. The all events happening in a menstrual cycle repeats themself every 28 days in a women with regular menstrual cycles.

Figure-2 (below) shows that there is no change in blood levels of FSH, LH, Estradiol, and Progesterone throughout a menstrual cycle without ovulation (anovulation). For this reason, the small sac with an egg does not grow and the egg is not released from the ovary which is shown in figure-2 (below). Pregnancy does not occurin women with anovulation because there is no egg released from the ovary to meet with a sperm and also menstrual bleeding will not happen in these women.

The small sac containing an egg does not grow or grows slowly which causes lack of ovulation and periods or delayed ovulation and periods in some women with polycystic ovary syndrome (Group A and B) that is shown in the left side of blue arrow in figure-2. However, there is no problem in the right side of blue arrow (figure-1) in women with polycystic ovary syndrome. That’s why, menstrual bleeding of a woman will begin about 14 days after ovulation whether she has polycystic ovary syndrome or not. For example; if the sac containing an egg grows and therefore ovulation occurs in 14 days, intervals between periods will be (14+14): 28 days. If the sac containing an egg grows and therefore ovulation occurs in 60 days, intervals between periods will be(60+14): 74 days. If the sac containing an egg grows and therefore ovulation occurs in 180 days, intervals between periods will be (180+14): 194 days.

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