Menstrual Cycle
Menstrual Cycle
● A female reproductive years begin around 11 to 13 years of age at the onset of menses
and end around age 50, when menses ceases.
● The average menstrual cycle is approximately 28 years in length, beginning with the first
day of menstrual bleeding.
● Premenarche is the physiological status of pre puberty , the time before the onset of
menses.
● Menarche is the state after reaching puberty in which menses occur normally every 28
days.
● Menopause refers to the cessation of menses.
Follicular Development and Ovulation
● During the menarcheal years, an ovum is released once a month once a month by one of
the two ovaries.
● All ova begin development during embryonic life and remain in suspended animation
within pre-antral follicle as an immune oocyte until the onset of menarche.
● Each ovary contains approximately 200,000 oocytes at the time of birth.
● When a young girl reaches puberty, the hypothalamus begins the pulsatile release of
gonadotropin releasing hormones.
● Which stimulates the anterior pituitary gland to secrete varying levels of gonadotropin(
primarily follicle-stimulating hormone and luteinizing hormone).
● The luteinizing hormone level will typically increase rapidly 24 to 36 hours before
ovulation in a process known as LH surge.
● It is the LH surge, accompanied by a smaller FSH surge that triggers ovulation in day 14.
Menstrual Cycle
● After ovulation, the ovary enters the luteal phase. This phase begins with ovulation and is
14 days in length.
● During Luteal Phase, the cells in the lining of the rupture ovarian follicle begin to
multiply and create corpus luteum or yellow body.
● The corpus luteum immediately begins secreting progesterone.
● As progesterone levels decline, menstruation occurs and the cycle begins.
Anatomy and physiology of female pelvis
● Two approaches are used to sonographically evaluate the female pelvis: transabdominal
and endovaginal(transabdominal).
● Transabdominal requires a full bladder for acoustic windows. Requires the 3.5 to 5 MHz transducer for adequate penetration.
● An edovaginal examination is performed with empty bladder and uses a 7.5 to 10 MHz
transducer.
