The menstrual cycle describes the monthly changes women's bodies go through from the start of menstruation to ovulation and then back to menstruation. It involves both ovarian and uterine cycles controlled by hormones. The ovarian cycle consists of the follicular phase where an egg develops and is released at ovulation, and the luteal phase where the corpus luteum forms. The uterine cycle involves changes to the endometrium driven by hormones, from proliferation to secretion to menstruation. Key events include the development and rupture of the ovarian follicle, formation and regression of the corpus luteum, and shedding of the uterine lining if implantation does not occur.

1. MENSTRUAL CYCLE
Kshyanaprava Behera
Assistant Professor
SOA University

2. WHAT IS Menstruation?
• The process in a woman of discharging
blood and other material from the lining of
the uterus at intervals of about one lunar
month (28 days) from puberty until the
menopause, except during pregnancy.

3. Menstrual cycle
• Menstruation is not the same as the menstrual
cycle.
• The Menstrual cycle describes the cyclic
changes in a woman’s body going through
menstruation, the follicular phase, ovulation,
the luteal phase and back to menstruation again to
begin the cycle.
• Menstruation is therefore one of the 4 phases
of the menstrual cycle.

4. Importance
• Cycle of natural changes that occurs in the uterus
and ovary as an essential part of making sexual
reproduction possible.
• Essential for the production of eggs.
• Preparation of the uterus for pregnancy.
• Fertile period of a woman’s life between
menarche and menopause.

5. Key terminologies
• Menarche: Age at onset of menstruation , 9 year to
16 year.
• Primary amenorrhea: Absence of menstruation
despite signs of puberty
• Secondary amenorrhea: Absence of menstruation
for 3-6 months in a woman who previously
menstruated
• Dysfunctional uterine bleeding: Irregular bleeding
due to anovulation or anovulatory cycle

6. • Menorrhagia: Regular menstrual intervals,
excessive flow and duration
• Metrorrhagia: Irregular menstrual intervals,
excessive flow and duration
• Oligomenorrhea: Menstrual interval greater
than 35 days
• Anovulation / anovulatory: Menstrual cycle
without ovulation
• Dysmenorrhea: Menstrual cramping/pain

7. Normal features of menstruation
1. Duration of menstrual flow
2. Quality of the menstruum,
3. Amount of blood loss,
4. The flow pattern and
5. Associated symptoms.

8. Duration
• Last from 3 to 7 days.
• The exact duration varies from woman to woman.
• It however shows little or no variation for the
same woman from cycle to cycle.
• Most women do not experience cycle to cycle
changes more than 1 or 2 days.
• It is unusual for the same woman to have wide
swings such as 3 days duration in one cycle and 7
days in another.

9. • Menstrual blood is normally bright or light
red in color like the bleeding that occurs after
a knife cut or similar injury.
• It could look brown in some few women and
still be normal menstruation.
• It must not have a foul odor.
• Small clots may be a normal part of menstrual
blood.

10. Amount of blood loss
• The average blood loss during normal
menstruation is about 35 ml, with a range of 10
to 80 ml.
• Usually understood from the number of
pads soaked.

11. The flow pattern
• Normally, as menses begin to flow, the
amount of blood loss seems to increase
gradually until it attains a maximum and
then starts diminishing as the end of the
flow draws near.
• This pattern is described as
crescendodecrescendo pattern.

12. Associated symptoms
• Normal menstruation may be accompanied by
other symptoms such as
Breasts fullness,
Mild lower abdominal pain or Irritability.
Fluid retention
Cramping
Mood swings
Weight gain
Breast tenderness
Diarrhea
Constipation

13. Hormone Control of Cycle
Hypothalamo-pituitary-ovarian axis
• Cycle controlled by hypothalamus, however this
can be influenced by higher centres within the brain
• i.e. due to stress or anxiety
• Hypothalamus releases gonadotrophin releasing
hormone in pulsatile manner
anterior pituitary release of LH and FSH

14. Hormone Control
• Follicular stimulating hormone (FSH) –
glycoprotein
• Stimulates follicular maturation during follicular
phase
• Stimulates steroid hormone secretion – oestrogen
(by the granulosa cells of mature ovarian follicle)
• Lutenizing Hormone (LH) – glycoprotein
• Stimulates steroid hormone secretion – oestrogen
• Ovulation – mid-cycle surge of LH
• Progesterone production by corpus luteum
• Negative feedback mechanism controls cycle

16. Phases of menstrual cycle

17. Ovarian Cycle – Follicular Phase
 Days 1-8 – FSH and LH relatively high levels
o Stimulate development of 10-20 follicles
o Results in full maturation of a single dominant
follicle – appearing in midfollicular phase
o Remainder undergo atresia
o High LH and FSH triggered by drop in oestrogen
and progesterone levels from last cycle .
o Oestrogen levels start to rise as follicular
development occurs

18. Ovarian Cycle – Follicular Phase (2)
• Days 9-14 –
o Follicle increases in size
o Localized accumulation of fluid among granulosa cells,
fluid-filled central cavity called antrum
o Transforming primary follicle to Graafian follicle
o Oocyte occupies excentric position – surrounded by
cumulus oophorus – 2-3 layers of granulosa cells
o Rise in oestrogen by granulosa cells, associated with
follicular maturation
o Inhibin produced by granulosa cells – restricting number
of follicles maturing

21. Ovarian Cycle - Ovulation
• Day 14 – rapid enlargement of follicle and rupture of
the follicle with extrusion of the oocyte and adherent
cumulus oophorus
• Some women get pain before rupture – called
Mittelschmerz
• Rise in oestrogen ,mid-cycle surge of LH and to a
lesser extent FSH then ovulation occure
• Immediately before ovulation there is a drop in
oestrogen and an increase in progesterone.
• Ovulation follows within 18 hours of midcycle surge of
LH
• If not enough of a LH surge – then no ovulation occurs
– anovulatory

22. Ovarian Cycle - Luteal Phase
• Days 15-28 – remainder of the follicle retained in
the ovary – penetrated by capillaries and
fibroblasts from the theca
• Grunlosa cells undergo luteinization called corpus
luteum formation – the major source of sex
hormones – oestrogen and progesterone secreted
during postovulary phase
• This leads to marked increase in progesterone
and oestrogen

23. Ovarian Cycle
If conception and implantation occur:
• Corpus luteum doesn’t regress – maintained by
gonadotrophins secreted by trophoblasts.
If conception doesn’t occur successfull:
• Corpus luteum regresses and menstruation occurs
• Drops in steroid sex hormones leads to a rise in
gonadotrophin levels (FH and LSH) that initiate next
cycle

26. Uterine Cycle
• Influenced by the cyclical production of steroid
hormones
• Causes changes to the uterus
• Involving the endometrium and cervical mucus

27. Uterine Cycle – Endometrium Overview
• Two layered
• Superficial layer that sheds during the menstrual
cycle
• Basal layer that doesn’t take part, but regenerates
the superficial layer
• The basal layer has straight arterioles where as the
superficial layers has spiral ones – important in the
process of shedding

29. Uterine Cycle – Proliferative Phase
• Occurs during follicular phase of ovarian cycle
• Endometrium exposed to oestrogen, regeneration
from the last menstrual cycle occur
• Glands in endometrium are straight in this phase,
parallel to one another and contain little secretion

30. Uterine Cycle – Secretory Phase
• After ovulation – progesterone production
causes secretory changes in endometrial glands
• Appearance of secretory vacuoles in glandular
epithelium below nuclei
• Secretions in lumen of glands which become
tortuous and develop serrated margins

31. Uterine Cycle – Menstrual Phase
• Luteal phase lasts 14 days – then there is a
regression of corpus luteum → decline in
oestrogen and progesterone
• This leads to a intense spasmodic contraction of
spiral section of endometrial arterioles →
ischaemic necrosis → shedding of superficial layer
→ bleeding.
• These spasms are associated with prostoglandin,
which are also associated with increased uterine
contractions during menstrual flow.

32. Cervical Mucus
• Important to stop ascending infection
• Changes during the menstrual cycle
• Early follicular phase – viscid and impermeable
• Late follicular phase – increasing oestrogen levels
mucus becomes watery and easily penetrated,
allowing spermatozoa to get through. Change is
known as Spinnbarkheit
• Post-ovulation – progesterone from corpus luteum
counteracts oestrogens effects mucus becomes
impermeable and the cervical os contracts

33. Other Changes
• Body temperature – Rise of 0.5°C after ovulation
till onset of menstruation. Due to progesterone
levels.
• If conception occurs – this temperature is
maintained throughout pregnancy
• Breast changes – breast swelling during luteal
phase due to increasing progesterone levels
• Psychological changes – change in mood and an
increase in emotional lability. Might be due to
falling progesterone levels.

36. THANK YOU