Menstruation

What is menstruation?

Menstruation is the elimination of the thickened lining of the uterus (endometrium) from the body through the vagina. Menstrual fluid contains blood, cells from the lining of the uterus (endometrial cells) and mucus. The average length of a period is between three days and one week.

Diagram of menstrual cycle

Diagram of menstrual cycle

Phases of menstruation:

Follicular phase

The follicular phase starts on the first day of menstruation and ends with ovulation. Prompted by the hypothalamus, the pituitary gland releases follicle stimulating hormone (FSH). This hormone stimulates the ovary to produce around five to 20 follicles (tiny nodules or cysts), which bead on the surface. Each follicle houses an immature egg. Usually, only one follicle will mature into an egg, while the others die. This can occur around day 10 of a 28-day cycle. The growth of the follicles stimulates the lining of the uterus to thicken in preparation for possible pregnancy.

Ovulation:

Ovulation is the release of a mature egg from the surface of the ovary. This usually occurs mid-cycle, around two weeks or so before menstruation starts. During the follicular phase, the developing follicle causes a rise in the level of estrogen. The

hypothalamus in the brain recognizes these rising levels and releases a chemical called gonadotrophin-releasing hormone (GnRH). This hormone prompts the pituitary gland to produce raised levels of luteinizing hormone (LH) and FSH. Within two days, ovulation is triggered by the high levels of LH. The egg is funnelled into the fallopian tube and toward the uterus by waves of small, hair-like projections. The life span of the typical egg is only around 24 hours. Unless it meets a sperm during this time, it will die.

Luteal phase:

During ovulation, the egg bursts from its follicle, but the ruptured follicle stays on the surface of the ovary. For the next two weeks or so, the follicle transforms into a structure known as the corpus luteum. This structure starts releasing progesterone, along with small amounts of estrogen. This combination of hormones maintains the thickened lining of the uterus, waiting for a fertilized egg to stick (implant).If a fertilized egg implants in the lining of the uterus, it produces the hormones that are necessary to maintain the corpus luteum. This includes human chorionic gonadotrophin (HCG), the hormone that is detected in a urine test for pregnancy. The corpus luteum keeps producing the raised levels of progesterone that are needed to maintain the thickened lining of the uterus. If pregnancy does not occur, the corpus luteum withers and dies, usually around day 22 in a 28-day cycle. The drop in progesterone levels causes the lining of the uterus to fall away. This is known as menstruation. The cycle then repeats.

Common menstrual problems:

Premenstrual syndrome (PMS) – hormonal events before a period can trigger a range of side effects in women at risk, including fluid retention, headaches, fatigue and irritability. Treatment options include exercise and dietary changes Dysmenorrhea – or painful periods. It is thought that the uterus is prompted by certain hormones to squeeze harder than necessary to dislodge its lining. Treatment options include pain-relieving medication and the oral contraceptive

pill.

Heavy menstrual bleeding (previously known as menorrhagia) – if left untreated, this can cause anaemia. Treatment options include oral contraceptives and a hormonal intrauterine device (IUD) to regulate the flow. Amenorrhea – or absence of menstrual periods. This is considered abnormal, except during pre-puberty, pregnancy, lactation and post menopause. Possible causes include low or high body weight and excessive exercise.

Cryptomenorrhea – is a condition where menstruation occurs but is not visible due to an obstruction of the outflow tract. Specifically the endometrium is shed, but a congenital obstruction in the vagina or on part of the hymen retains the menstrual flow. A patient with cryptomenorrhea will appear to have amenorrhea but will experience cyclic menstrual pain. The condition is surgically correctable.

Polymenorrhea – is a term used to describe a menstrual cycle that is shorter than 21 days. A normal menstrual cycle is between 24 and 38 days long. Polymenorrhea is just one form of abnormal uterine bleeding.

Oligomenorrhea – is a condition in which you have infrequent menstrual periods. It occurs in women of childbearing age. Some variation in menstruation is normal, but a woman who regularly goes more than 35 days without menstruating may

be diagnosed with oligomenorrhea.

Menorrhagia – is the medical term for menstrual bleeding lasting for longer than 7 days. It is the medical term for menstrual periods with abnormally heavy or prolonged bleeding. Menorrhagia can lead to anemia if not treated.

Metropathia – abnormal, excessive, often continuous, uterine bleeding due to persistence of the follicular phase of the menstrual cycle.

DUB (dysfunctional urinal bleeding) – is a condition that causes vaginal bleeding to occur outside of the regular menstrual cycle. Abnormal uterine bleeding or dysfunctional uterine bleeding is irregular uterine bleeding that occurs in the absence of recognizable pelvic pathology, general medical disease, or pregnancy