Dr Ismaiel Abu Mahfouz · 2019. 9. 16. · Dr Ismaiel Abu Mahfouz . Menstruation Definition A...
Transcript of Dr Ismaiel Abu Mahfouz · 2019. 9. 16. · Dr Ismaiel Abu Mahfouz . Menstruation Definition A...
The menstrual cycle
Dr Ismaiel Abu Mahfouz
Menstruation
Definition
A woman's monthly bleeding from the reproductive
tract induced by hormonal changes of menstrual
cycle
For menstruation to occur
• Coordinated HPO axis
• Responsive endometrium
• Patent outflow
The menstrual cycle hormones
GnRH
• A peptide hormone
• Synthesized and released from GnRH neurons in
hypothalamus
• Responsible for the release of FSH & LH from
anterior pituitary
FSH
• A glycoprotein polypeptide hormone
• Granulosa cell proliferation and differentiation
• Antral follicle development
• Oestrogen production
• Inhibin synthesis
• Induction of LH receptors on dominant follicle
LH
• A glycoprotein hormone
• The main promoter of constant androgen
production from the theca cell
• The pre-ovulatory LH surge
o Triggers ovulation and follicular rupture
o Induces resumption of oocyte meiotic
maturation
o Causes luteinization of granulosa cells
(formation of corpus luteum)
Estradiol
• Suppresses FSH due to a -ve feedback leading to
selection of a dominant follicle
• Triggers LH surge due to a +ve feedback
• Increases endometrial thickness
• Stimulates cervical glands to secrete a particular
type of mucus which is essential for sperms to
pass through
Progesterone
• Induces secretory endometrium to enhance
embryo implantation
• Maintains endometrium in 1st week of pregnancy
• Modifies endometrial glandular structure (more
number, more tortuous)
• Involved in gene expression in endometrium
needed for implantation
Inhibin
• Two hormones : Inhibin A & B
• Secreted by granulosa cells in ovary
• Inhibits production of FSH via –ve feedback
• Involved in control of gamete production,
embryonic and fetal development
Hormonal interaction
GnRH
Sex steroids
- Esradiol
- Progesterone
Gonadotropins
- FSH
- LH
The menstrual cycle
• The ovarian cycle
• The endometrial cycle
The ovarian cycle
The Ovarian Cycle
Follicular phase (pre-ovulatory)
• Recruitment & selection of dominant follicle
• Increasing levels of estradiol & inhibin B
Ovulatory phase
• LH surge
• Rupture of pre-ovulatory follicle wall
• Release of viable ovum
Luteal phase (post-ovulatory)
• Corpus luteum development
• Increasing levels of progesterone
• Secretory changes in endometrium
Menstrual phase
Follicular Phase
• A group of the most mature follicles (called “antral
follicles”) are recruited
• Only follicles most sensitive to FSH undergoes a
further development
• Follicle most sensitive to FSH continue to
develop and produce a large amount of estradiol
and inhibin B
• Remaining follicles become atretic (99%)
Ovulatory phase
• An event in the menstrual cycle by which a
selected mature follicle breaks and releases a
viable oocyte
• Each month, one egg is released ; occasionally,
two or more
• If pregnancy does not occur, menstruation
starts after exactly two weeks
Ovulatory phase
Mechanism of follicle rupture
• Increase of intra-follicular pressure
• Perifollicular ovarian smooth muscle contractions
• Vascular alterations in peri-follicular vessels
• Prostaglandins and proteolytic enzymes
• Cytokines, O2 free-radicals, nitric oxide and
angiotensin II
Ovulatory phase
Ovulation
• Ovulation occurs 34-36 hours after onset of LH surge
Luteal phase
• Peak level of progesterone occurs 7 days after ovulation
• This approximates the time of implantation
• In early pregnancy, hCG maintains luteal function with secretion of progesterone until placental steroidogenesis is established
Menstrual phase
• Rapid ↓ in steroids → shedding of the unused
endometrium
• Inflammatory mediators (PGs, ILs, and TNF) →
vasospasm in spiral arteries → hypoxia and
endometrial devitalisation
• Haemostatic mechanisms will be activated
including platelet plugs, coagulation cascade,
and fibrinolysis
• Endometrium shed down to basalis layer
Phases of the endometrium
Duration
• 2-8 days
Estrogen
• Variable
• Vascular growth
Progesterone
• Fixed 14 days • Gland tortuosity & secretion,
stromal oedema ,decidual reaction of the endometrium
Endometrial breakdown
• Basalis layer remains Undergoes repair
• Endometrium is protected from the lytic
enzymes in the menstrual fluid by mucinous
layer of carbohydrate products secreted from glands and stromal cells
Menstrual Fluid
• Autolysed functionalis layer
• Inflammatory exudate
• RBC
• Proteolytic enzymes (mainly plasmin)
If rate and flow are high clots are formed
Estrogen
LH surge
GnRh
E
Hypothalamus
FSH
follicle
Ant. Pituitary
Inhibin
Dominant follicle
Ovulation
-VE
+Ve
Cervical changes
Follicular phase Luteal phase
Internal os: funnel shape Tightly closed
Mucus: thin &watery Thick & viscid
Stretchability: increased Lost
Normal menstrual cycle
Menstrual cycle should be described according to
four specific symptomatic components
• Frequency
• Duration
• Volume
• Regularity
Normal Menstrual Cycle
Frequency (Length) • Mean is 28 days +/- 7 days
• Menstrual cycle tends to shorten with age
• Initially irregular
Duration of menstruation • Normal range: 4.5 – 8.0 days, Mean: 5 days
• Prolonged >8 days, shortened < 4.5 days
• With advancing age: duration decreases
Volume of menstrual blood loss (ml) • Range: 20 – 50 mls, Mean 40 ml
• Heavy >80 ml; light < 5 ml