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.