Menstruation Cycle

Menstruation is a periodic uterine bleeding in response to cyclical hormonal changes. It begins at puberty and ends at menopause. Most women have 28-day cycle period. Length is about 2-7 days. The structures involved are the hypothalamus, pituitary gland, ovaries, and uterus.

The menstruation cycle consist of:

I. Uterine Phase

a. Menstrual phase - days 1-5
- endometrial lining is shed
- lutenizing hormone (LH), estrogen and progesterone at their lowest level
- follicle stimulating hormone (FSH) increases, that graafian follicle begins maturing

b.Proliferative phase - days 6-14
- uterine lining grows due to increase estrogen; it thickens by 8-10 folds
glands and vascularization are developed 3-4 days before ovulation

c. Ovulation - days 12-16
- estrogen is high and progesterone is low
- release of mature, non-fertilized ovum
- spinnbarkeit - stretchable cervical mucus

d. Secretory or Luteal phase - 15-23 days
- uterus is prepared for implantation
corpus luteum produces large quantities of estrogen and progesterone
- if fertilization takes place, implantation occurs 7-10 days post fertilization. Trophoblast produces human chorionic gonadotropin (HCG)

II. Ovarian Phase

a. Premenstrual or Ischemic Phase - days 24-28
- no fertilization takes place
endometrial arteries constricts; Corpus luteum regresses, uterus shrinks
- decreased estrogen and progesterone

menstrual concerns are:

Metrorrhagia - bleeding in between menses
Menorrhagia - excessive menstruation
Menopause - cessation of menses
Amenorrhea - absence of menses
Dysmenorrhea - painful, difficult menstruation

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