S4 The menstrual cycle Flashcards
what is the ovarian cycle ?
preparation of the gamete
what is the uterine cycle ?
prepraration of the endometrium
what is the waiting phase in the menstrual cycle
maintaining the endometrium until a signal is recieved to indicate that fertilisation has happened
what is the menstrual cycle controlled by ?
gonadotrophins acting on the ovary and ovarian steroids acting on tissues of the reproductive tract
what are the two phases of the ovarian cycle known as
follicular phase and luteal phase
what are the 3 phases of the endometrial cycle
mense , proliferative phase, secretory phase
describe what happens at the start of the cycle - FSH
no ovarian hormone production, early development of follicles begins
low steroid and inhibin levels
little inhibition at the hypothalamus or anterior pituitary so FSH levels rising
describe the secretion of gonadotrophins and gonadal steroids over the menstrual cycle at the beginning
FSH binds to granulosa cells and theca interna appears, allowing secretion of oestrogen and inhibin (low concentration, so little inhibition at H/AP so FSH increases)
describe the secretion of gonadotrophins and gonadal steroids over the menstrual cycle at the mid-follicular phase
nomination of dominant follicle, follicular oestrogen at high concentration so positive feedback on Hypo and AP
describe the secretion of gonadotrophins and gonadal steroids over the menstrual cycle at the pre-ovulation phase
rapid increase in oestrogen and inhibin causes LH surge (FSH doesnt rise as inhibited by inhibin). GnRH pulses get more rapid in preparation for ovulation. progesterone production begins : granulosa cells become responsive to LH
describe the secretion of gonadotrophins and gonadal steroids over the menstrual cycle at the ovulation cycle
meiosis 1 completed, meiosis II starts, mature ooctye extruded through capsule of ovary
describe the secretion of gonadotrophins and gonadal steroids over the menstrual cycle at the luteal phase
a follicle is luteinised by LH making the corpus luteum; secretes oestrogen, progesterone and inhibin. LH suppressed by negative feedback due to the presence of progesterone - waiting phase
since LH is suppressed, corpus luteum regresses spontaneously after exactly 14 days (unless fertilisation occurred)
end of cycle : CL regresses and get menses, resets to start
describe the secretion of gonadotrophins and gonadal steroids over the menstrual cycle during pregnancy
if fertilisation has happened the syncytiotrophoblast produces HCG which has a lutenising effect supporting CL. CL produces steroid hormones to support the pregnancy. eventually placenta is capable of producing enough steroid hormones to control the HPO axis throughout pregnancy
how does the lining of the uterus respond to oestrogen
the lining of the uterus, endometrium responds to oestrogen by proliferating and responds to oestrogen and progesterone by secreting
myometrium responds to oestrogen and progesterone but does not shed during the cycle
what are the two layers of the endometrium
Functional layer (F) is hormone responsive and is shed if no pregnancy occurs Basal layer (B) provides the source from which a new functional layer is developed
what are changes to the uterus over the uterus cycle
early proliferative : glands sparse, straight
late proliferative : functional layer has doubled, glands now coiled
early secretory : endometrium max thickness, very pronounced coiled glands
late secretory : glands adopt characteristics “saw-tooth” appearance
list the actions of oestrogen and progesterone (gonadal steroids) in a non -pregnant women
follicular phase - oestrogen thickening of endometrium thin alkaline cervical mucus - promotes fertilisation changes in the vagina, skin, hair growth and motility of myometrium
Luteal phase -- progesterone endometrium becomes secretory increased body temperature thickens myometrium thick, acidic cervical mucus - limits infection risk and access for sperm
what is the cycle duration
length 21-35 days , variation is due to length of follicular phase. Luteal phase strictly controlled at 14 +/- 2 days. occurs monthly unless affected by pregnancy (high O and P so shuts down axis), lactation, low body weight
what is amenorrhea
absence of menstruation
primary : failure to establish menstruation by 16 years
secondary : cessation of previously normal menstruation for >/= 6 months
physiological causes : prepubertal, pregnancy , menopause
gonadotrophin levels indicate level of pathology
what is oligomenorrhea
infrequent menstruation, >35 days i.e. 4-9 times a year
what is menorrhagia/heavy menstrual bleeding (HMB)
a complaint of excessive menstrual blood loss over consecutive cycles
common causes : uterine fibroids - leiomyoma, Uterine polyps , endometrial cancer, drugs e.g warfarin
what is dysmenorrhoea
pain during menses, associated with ovulatory cycles; the higher presence of prostaglandins cause uterine contractions which reduce uterine blood flow – ischaemia (IMB) intermenstrual bleeding
primary is idiopathic, due to response of the uterus to local prostaglandins, hence painful contractions. Secondary can be due to endometriosis or obstructed menses
what is dysfunctional uterine bleeding (DUB)
a heavy and irregular menstrual bleeding that occurs secondary to anovulation
what is premenstrual syndrome (PMS)
a cyclical disorder, occuring in latter half of the menstrual cycle. Symptoms could be physical or psychological and resolve with onset of menstruation
what is premenstrual dysphoric disorder
is the severe end of the spectrum with extreme mood symptoms
what are the common causes of menstrual disorders
can be hormonal - HPO axis
chromosomal anomalies e.g XO- turner’s syndrome ; androgen insensitivity syndrome ; Swyer syndrome
Structural/anatomical - e.g fibroids, polyps
other : drugs, thyroid disease, chronic illness
what are the structural causes of menstrual disorders ?
hypoplasia at any level of the genital tract
leiomyoma - uterine fibroids
imperforate hymen, cervical stenosis
describe irregular bleeding in terms of menstruation
a feature of hormonal contraception, especially the progesterone-only pill other causes : - STI's - Cervical pathology - Endometrial polyp or cancer - ovarian cyst
what is endometriosis
endometrial glands or stroma growing outside of the uterine cavity, typically confined to pelvis but can spread. Endometrial tissue passes out of fallopian tube and implants on a peritoneal structure. Symptoms include pain, infertility, hypermenorrhoea, haematuria. Pain is dull, bilateral and can be very severe, occurring just before or during menstruation
what is pre-menstrual syndrome (PMS)
is subjective, cyclical and can be distressing. Severe form -premenstrual dysphoric disorder
what is the assessment and management of the menstruation disorders
history
- comprehensive history - emphasis on age ; onset of puberty
-menstrual history - cycle, volume change etc
- sexual history , medical history , symptoms of effects
examination
- general,abdominal
- swellings/lumps/masses
investigation
bloods, FBC, hysteroscopy (camera in uterus), laparoscopy (camera in abdomen)
management
correct the underlying condition
pharmacological cause - use of gonadotrophins , progesterone
