Menstrual cycle Flashcards
What three things must a woman have to have a normal menstrual period?
Normal HPO axis
Responsive endometrium
Patent outflow tract
When is the clinical dating of the menstrual cycle?
From the first day of the last period
What happens in the preparation phase of the menstrual cycle?
Follicles grow in the ovary
The cervix prepares to allow sperm in (opens)
Uterus proliferates Sexual interaction facilitated
Describe the events of the early follicular phase
Begins as menstrual shedding starts. Oestrogen returns to basal levels Hypothalamus and pituitary free from negative feedback. FSH and LH begin to rise in the absence of negative feedback from oestrogen (FSH raised more due to lack of inhibin). FSH stimulates granulosa cells, and LH stimulates theca cells. Follicles begin to grow
Which hormone is dominant in the mid-follicular phase?
Oestrogen Released by the follicle as it develops and grows
Describe the events of the mid-follicular phase
As follicles grow they secrete oestrogen and inhibin. This exerts negative feedback on FSH and LH. FSH is selectively depressed by inhibin, which means that no more follicles are recruited to mature. FSH falls more than LH. One follicle becomes dominant and matures (antral follicle/ Graafian follicle).
Motility of the oviduct and myometrium increase to encourage movement of the ova towards the ampulla.
The endometrium begins to proliferate and the cevix secretes a thin alkaline mucus when open which creates a favourable environment for the sperm.
Changes occur in vagina secretions, skin, hair and metabolism
What are the three layers of the uterus?
Endometrium (inner)
Myometrium (outer)
Perimetrium (outer coat)
What are the layers of the endometrium?
Strata functionalis (has compact and spongy layers)
Bastalis
What are the key events at the end of the follicular phase?
One follicle has become dominant (Graafian follicle) and levels of oestrogen rise rapidly, resulting in positive feedback on LH.
This produces the LH surge required for ovulation
What happens to the uterus in the follicular phase?
It begins to proliferate (endometrium layers grow in preparation for the conceptus)
Describe the changes that occur in ovulation
After the LH surge the Graafian follicle ruptures and the ova is released into the peritoneum (causes mid-cycle pain). Some fluid is also released which can irritate the peritoneum.
Mid-cycle can occur due to a temporary drop in oestrogen post-ovulation.
Describe the events of the luteal phase
THe disrupted follicle forms teh corpus luteum. This secretes oestrogen and progesterone.
LH, FSH and GnRH are suppressed by negative feedback.
The corpus luteum lasts 14 days and then regresses. This is the least variable part of the cycle.
The myometrium becomes quiescent and continues to proliferate.
Cervix secretes a thick acidic mucus which kills any sperm in the vaginal tract.
There is decreased libido, an increase in temperature, water retention and bloating due to testosterone.
Describe the events at the end of the luteal phase if the ova is not fertilised
The corpus luteam undergoes apoptosis if fertilisation fails to take place.
Levels of oestrogen and progesterone fall and the endometerium begins to shed (menstruation)
The pituirary and hypothalamus are freed from feedback inhibition.
LH anf FSH begin to rise to start a new cycle.
Describe the events at the end of the luteal phase if there is fertilisation
The conceptus implants into the endometrium and forms trophoblast layers which secretes hCG.
hCG maintains the corpus luteum to continue to secrete progesterone and oestrogen until the placenta has developed (10-12 weeks)
What are the three classic symptoms of the menopause?
Hot flushes
Sweats
Vaginal dryness
What is the menopause?
Cessation of the menses.
Normally occurs between 45-60. Decline is gradual as ovarian oestrogen levels are progressively reduced. Periods space out and cease.
Symptoms are primarily due to falling oestrogen levels
Name four other symptoms a women may experience when going through the menopause?
Non-specific: Headaches, migranes, palpitations, disturbed sleep
Urogenital symptoms: vaginal dryness, cystitis, urinary frequency, urinary incontinence
Psychological: Loss of concentration, poor memory, irritability, loss of libido
Atrophy of connective tissue: skin thinning, hair loss, brittle nails, aches and pains, osteoporosis
What is the normal onset of menarche?
11-15 years
What is the average length of a normal menstrual cycle?
21-42 days
How much blood is lost during menstrual flow?
30-120ml
What are the important things to ask a patient who presents with menstrual problems
Menstrual history:
What is the normal cycle period?
Has there been an increase or decrease in normal flow?
ICE
Symptoms of anaemia
Metrorrhagia
Heavy irregular periods
What are the categories of abnormal bleeding?
No bleeding
Abnormal uterine bleeding
Early pregnancy complications
Causes of dysmenorrhea
Painful periods
Primary: no pathology, due to increased release of prostaglandins. Treated with NSAIDs, time. Common in adolescents
Secondary: occurs in middle reproductive years, pathological e.g. endometriosis
Endometriosis
Caused by ectopic endometrial glands and stroma.
Causes a cyclical pain due to the action of hormones regulating the menstrual cycle.
Symptoms include dysmenorrhoea, dyspareunia, irregular periods.
Causes of amenorrhea
Primary amenorrhoea - no menarche by age 16
Secondary - over 3-6 months with no period.
Can be physiological or pathologic
Name four physiological causes of amenorrhoea
Pre-puberty
Pregnancy
Lactation
Menopause
Puerperium
Name four pathologic causes of amenorrhoea
Hypothalamic control (altered in anorexia and stress)
Pituitary tumor
Dysgenesis ot damage to the ovary
Damage to the uterus
Imperforate hymen
What tests would you do in a patient who is amenorrheic?
Pregnancy test
Oestrogen levels
FSH levels
Hb/Hct levels
Thyroid hormone levels
Karyotype
Name three causes of abnormal uterine bleeding
Endometrial cancer
Cervical cancer
Fibroids
Endometrial polyps
What are fibroids?
The common name for uterine leiomyomas (benign smooth muscle neoplasms) which occur in the myometrium.
Leiomyomas are well defined, round, firm, gray-white tumors surrounded in a pseudocapsule. Can be submucosal, intramural or subserosal. May be asymptomatic even if extensive.
Can cause abnormal bleeding, compression of the bladder (causing urinary frequency), pain and impaired fertility.
Name three causes of bleeding in early pregnacy
Implantation bleeding
Miscarriage
Molar pregnacy
Ectopic pregnancy.
How would you evaluate abnorma bleeding in a patient?
History: general, menstrual
Physical examination, pelvic examination
Blood tests: hCG, Hb levels
Possible pelvic ultrasound and endometrial sampling
What are the effects of oestrogen in the follicular/proliferative phase?
steadily rising titres of oestrogen stimulates:
secretion and muscular contraction in the fallopian tube, and the growth and motility of fallopian cilia
growth and motility of the myometrium
thickening of the endometrium, and secretion a watery fluid to help transport of sperm
secretion of thin alkaline cervical mucus
increased mitotic activity in the vaginal epithelium
mildly anabolic metabolic changes, depress appetite and affects the cardiovascular system
What are the actions of progesterone in the luteal/secretory phase?
the action of progesterone on oestrogen primed cells:
Reduces fallopian tube motility, secretion and cilia activity
Stimulates further thickening of the myometrium, but reduces motility
Stimulates further thickening of the endometrium, increased secretion and the development of spiral arteries
Stimulates thickening and acidity f cervical mucus, to prevent sperm transport
Stimulate a mildly catabolic metabolic change and increases basal body temperature
How would you evaluate abnorma bleeding in a patient?
History: general, menstrual
Physical examination, pelvic examination
Blood tests: hCG, Hb levels
Possible pelvic ultrasound and endometrial sampling
