Menstruation: Definition and Characteristics

Menstruation Definition

• A menstrual cycle is periodic uterine bleeding in response to cyclic hormonal changes in the ovary, uterus, and cervix.
• This process is part of a woman's reproductive cycle.
• The end of a woman's reproductive phase is called menopause (between ages 45-55).

Characteristics of Normal Menstrual Cycles

• Beginning: Menarche, the first menstrual period, is the most definitive sign of puberty, typically between ages 9 and 17 (average 12-13).
• Cycle Length: Average cycle length is 28 days, but ranges from 23 to 35 days.
• Duration: The average menstrual period lasts 3-5 days, but can range from 1 to 8 days.

Amount and Characteristics of Menstrual Flow

• Amount: Average menstrual flow is 30-100 cc, without clots. Heavy bleeding is defined as saturating a pad in less than an hour.
• Color: Dark red, a combination of blood, mucus, and endometrial cells.
• Odor: Typically described as marigold-like.
• Contents: Blood, mucus, endometrial shreds, desquamated vaginal epithelium, and leukocytes.

Physiology of the Menstrual Cycle

• Four structures involved: Hypothalamus, pituitary gland, ovaries, and uterus. All four must function for a complete cycle. Inactivity in any of these leads to incomplete or ineffective cycles.
• Hypothalamus: Initiates the cycle and releases Gn-Rh (gonadotropin-releasing hormone).
• Pituitary Gland: Produces FSH (follicle-stimulating hormone) and LH (luteinizing hormone) gonadotropin hormones.
• Ovaries: Produces estrogen and progesterone.
• Uterus: Thickens before menstruation, the endometrium tissue.

Phases of the Ovarian Cycle

• Follicular Phase: Begins the first day of menstruation and lasts 12-14 days. The Graafian follicle matures under the influence of FSH and LH. The follicle produces estrogen.
• Ovulatory Phase: Occurs when estrogen peaks, leading to ovulation (release of the oocyte from the Graafian follicle).
• Luteal Phase: Begins after ovulation, lasting about 14 days. Cells of the empty follicle become the corpus luteum which releases high levels of progesterone and low levels of estrogen.

Phases of the Endometrial Cycle

• Proliferative Phase: Begins after menstruation, and ends with ovulation. The endometrium thickens (3-4 mm) and becomes more vascular (straight arteries) in response to increasing estrogen levels.
• Secretory Phase: Begins after ovulation and ends with menstruation. The endometrium continues to thicken (6-8 mm). High progesterone levels cause glands to secrete mucin and glycogen. If pregnancy occurs, the endometrium continues to develop to support pregnancy. If not, the corpus luteum degenerates, the endometrium degenerates, and the cycle repeats with menstruation.
• Menstrual Phase: The shedding of the uterine lining (endometrial) due to decreased progesterone, creating conditions conducive to menstruation (loss of blood, mucus and endometrial material).

Health Teaching Points

• Exercise: Moderate exercise is beneficial, but avoiding excessive exercise is encouraged.
• Daily Activities: No activities are contraindicated.
• Pain Relief: Mild analgesics (like ibuprofen) are helpful. Applying heat can also relieve pain.
• Rest: Increased rest may be beneficial if pain interferes with sleep.
• Nutrition: Some iron supplementation may be necessary to replenish lost iron.