S4 The menstrual cycle

Question 1

what is the ovarian cycle ?

Answer 1

preparation of the gamete

Question 2

what is the uterine cycle ?

Answer 2

prepraration of the endometrium

Question 3

what is the waiting phase in the menstrual cycle

Answer 3

maintaining the endometrium until a signal is recieved to indicate that fertilisation has happened

Question 4

what is the menstrual cycle controlled by ?

Answer 4

gonadotrophins acting on the ovary and ovarian steroids acting on tissues of the reproductive tract

Question 5

what are the two phases of the ovarian cycle known as

Answer 5

follicular phase and luteal phase

Question 6

what are the 3 phases of the endometrial cycle

Answer 6

mense , proliferative phase, secretory phase

Question 7

describe what happens at the start of the cycle - FSH

Answer 7

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

Question 8

describe the secretion of gonadotrophins and gonadal steroids over the menstrual cycle at the beginning

Answer 8

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)

Question 9

describe the secretion of gonadotrophins and gonadal steroids over the menstrual cycle at the mid-follicular phase

Answer 9

nomination of dominant follicle, follicular oestrogen at high concentration so positive feedback on Hypo and AP

Question 10

describe the secretion of gonadotrophins and gonadal steroids over the menstrual cycle at the pre-ovulation phase

Answer 10

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

Question 11

describe the secretion of gonadotrophins and gonadal steroids over the menstrual cycle at the ovulation cycle

Answer 11

meiosis 1 completed, meiosis II starts, mature ooctye extruded through capsule of ovary

Question 12

describe the secretion of gonadotrophins and gonadal steroids over the menstrual cycle at the luteal phase

Answer 12

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

Question 13

describe the secretion of gonadotrophins and gonadal steroids over the menstrual cycle during pregnancy

Answer 13

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

Question 14

how does the lining of the uterus respond to oestrogen

Answer 14

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

Question 15

what are the two layers of the endometrium

Answer 15

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

Question 16

what are changes to the uterus over the uterus cycle

Answer 16

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

Question 17

list the actions of oestrogen and progesterone (gonadal steroids) in a non -pregnant women

Answer 17

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

Question 18

what is the cycle duration

Answer 18

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

Question 19

what is amenorrhea

Answer 19

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

Question 20

what is oligomenorrhea

Answer 20

infrequent menstruation, >35 days i.e. 4-9 times a year

Question 21

what is menorrhagia/heavy menstrual bleeding (HMB)

Answer 21

a complaint of excessive menstrual blood loss over consecutive cycles
common causes : uterine fibroids - leiomyoma, Uterine polyps , endometrial cancer, drugs e.g warfarin

Question 22

what is dysmenorrhoea

Answer 22

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

Question 23

what is dysfunctional uterine bleeding (DUB)

Answer 23

a heavy and irregular menstrual bleeding that occurs secondary to anovulation

Question 24

what is premenstrual syndrome (PMS)

Answer 24

a cyclical disorder, occuring in latter half of the menstrual cycle. Symptoms could be physical or psychological and resolve with onset of menstruation

Question 25

what is premenstrual dysphoric disorder

Answer 25

is the severe end of the spectrum with extreme mood symptoms

Question 26

what are the common causes of menstrual disorders

Answer 26

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

Question 27

what are the structural causes of menstrual disorders ?

Answer 27

hypoplasia at any level of the genital tract
leiomyoma - uterine fibroids
imperforate hymen, cervical stenosis

Question 28

describe irregular bleeding in terms of menstruation

Answer 28

a feature of hormonal contraception, especially the progesterone-only pill
other causes : 
- STI's
- Cervical pathology
- Endometrial polyp or cancer
- ovarian cyst

Question 29

what is endometriosis

Answer 29

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

Question 30

what is pre-menstrual syndrome (PMS)

Answer 30

is subjective, cyclical and can be distressing. Severe form -premenstrual dysphoric disorder

Question 31

what is the assessment and management of the menstruation disorders

Answer 31

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