1. Menstrual cycle and Ovulation
Dr. Patrick Idoko FWACS
Lecturer SMAHS UTG
Consultant Obstetrician & Gynaecologist RVTH

2. Menstruation
The periodic and cyclical shedding of the endometrium accompanied by loss of blood.

3. Normal menstrual cycle
A hormonally controlled process of events occurring through the hypothalamic-pituitary-ovarian axis in which if there is no implantation of a fertilized ovum, menstruation occurs.

4. Normal menstruation Usually lasts for 2- 7 days (5)
Normal cycle length days (28)
Average monthly blood loss: ml (40 ml)
Physiology of menstruation closely linked to factors controlling ovulation
Menstrual cycle is the time between 2 successive menstruations
Menstrual discharge contains red blood cells, endometrial cells, macrophages, mast cells, vaginal epithelial cells, prostaglandins and fibrinolysin

5. Hormonal interactions
Pituitary cycle
Ovarian cycle
Endometrial cycle

6. Hormonal interactions
Pituitary cycle
Pulsatile GnRH from Hypothalamus
Due to fall in Oestradiol, Progesterone and Inhibin levels from ovary
Stimulates release of FSH, LH from pituitary
Rising FSH causes ovarian follicular growth and maturity
In mid cycle, LH surge occurs resulting in ovulation hours after the peak

7. Hormonal interactions
Ovarian Cycle
Developing follicle produces Oestradiol from FSH and LH stimulation
Oestradiol stimulates proliferation of the endometrium
After ovulation, FSH and LH levels fall
Corpus luteum develops at the site of the ruptured follicle
Progesterone is secreted from the ovary

8. Hormonal interactions
Progesterone causes the endometrium to stabilize and differentiate
resulting in more tortuous glands
and
increased coiling of the spiral arteries.

9. Phases of the menstrual cycle
Menstrual phase
Superficial and middle layers of the endometrium are shed in an irregular haphazard way
Proliferative phase
Under the influence of oestrogen, thickness of the endometrium increases from 1 to 3 mm
Epithelial lining become columnar but no secretory activity
Secretory phase
Changes are due to the influence of predominantly progesterone on a previously E2 primed endometrium
Glands become tortous and distended with secretions
Lasts for 14 days

10. Ovarian cycle Follicular phase Ovulatory phase Luteal phase
Several primordial follicles enlarge with one growing faster
Ovulatory phase
The dominant follicle continues to grow and ruptures at about Day 14
Luteal phase
The ruptured follicle then forms the corpus luteum secreting progesterone predominantly

11. Menstrual and ovulatory cycle

12. Ovulation process
Follicles of all stages of development found within ovarian stroma
Folliculogenesis takes place in several steps
Growing follicles induce changes in surrounding cells which differentiate into granulosa and theca cells
FSH pushes responsive follicles into the final stages of maturation where ovulation is possible
LH surge produces follicular rupture
As the corpus luteum degenerates, progestrone falls and menstruation occurs

13. Mechanism of blood loss
Spiral arterioles sensitive to levels of sex hormone
Progesterone  constriction of arterioles  ischaemia shedding of upper ⅔ of endometrium

14. Dysmenorrhoea Pain during menstruation Primary: Secondary:
Absence of organic disease of the genital tract
Commonest in young post-menarchal girls
Begins hrs before onset of menstruation and regresses within 72 hours of menstruation
Usually due to excessive prostaglandins
Secondary:
Usually due to organic pelvic disease

15. Premenstrual Syndrome
Definition
Cyclic recurrence of physical, psychological or behavioral symptoms that appear after ovulation and resolve with the onset of menstruation
Severe enough to disrupt
personal relationships
Social activities
Job performance
True PMS only occurs in the luteal phase of the menstrual cycle with a symptom free period during the follicular phase
Most severe presentation of PMS known as Pre-menstrual Dysphoric Disorder (PMDD)