Week 2- contraception Flashcards
Describe the hypothalamic pituitary axis in relation to ovarian hormones?
Hypothalamus releases gonadotrophin releasing hormone which stimulates the anterior pituitary to release follicle stimulating hormone and luteinising hormone. this stimulates the ovaries to produce oestrogen and progesterone. Progesterone acts on the anterior pituitary via negative feedback, oestrogen acts on the hypothalamus via negative feedback.
What hormone spikes before ovulation?
LH
What does the release of follicle stimulating hormone have on the ovaries?
Causes the primary follicle to develop into the secondary follicle.
What do the ovaries release in response to follicle stimulating hormone?
Oestrogen
What effect does oestrogen have on the gonadal hormones?
In low concentrations- oestrogen inhibits LH
In high concentrations- it inhibits FSH.
Describe the follicular phase of menstruation?
GnRH is released causing the anterior pituitary to release FSH and LH. FSH causes the primary follicle to develop into the secondary follicle releasing oestrogen. The low levels of oestrogen suppress LH. As more oestrogen is produced it starts to inhibit FSH and LH levels spike. This spike causes ovulation.
Describe the luteal phase of menstruation
The oocyte has been released and the follicle is now dead. The LH dips again. The corpus luteum secretes several hormones as it is converted to the corpus albicans. These hormones are progesterone, oestrogen and inhibin. Progesterone inhibits GnRH release, oestrogen inhibits LH and inhibin prevents the release of FSH. Once it becomes the corpus albicans these hormones are no longer released and it becomes the corpus albicans.
How long do sperm last in the female reproductive tract?
5 days.
How long does the ovum survive for?
17-24 hours.
What is meant by pearl index?
Number of contraceptive failures per 100 women/year
What is meant by basal body temperature?
Temperature your body is at when you wake up in the morning.
What happens to the basal body temperature at ovulation?
It rises by above 0.2 degrees and is sustained.
At ovulation, what happens to the cervical mucous? What is the purpose of this?
It becomes thin and watery, to allow sperm to swim easier.
What position is the cervix in when a woman is fertile?
High in the vagina, soft and open.
What position is the cervix in when a women is not fertile?
Low in the vagina, firm and closed.
In a 28 day cycle, what day is the women most fertile?
8-18.
Is breastfeeding an effective contraception?
Yes- but you have to do it under certain conditions.
- exclusively breast feeding
- Amenorrhoeic
- Less than 6/12 post natal.
Give an example of IUS contraceptives and what does IUS mean?
Intra-uterine system- examples are the mirena coil and the Jaydess.
Give an example of IUD contraceptives and what does IUD mean?
Intra-uterine device- copper coil.
How does the combined oral contraceptive pill stop pregnancy?
What co-effects does it also have?
It secretes oestrogen and progesterone. Progesterone inhibits the release of FSH and LH and oestrogen inhibits the release of GnRH.
This means it inhibits ovulation.
It also makes cervical mucous more sticky and thick.
What is the pearl index for the combined OCP?
0.3%
What is the mode of action of the progesterone only pill?
What co-effects does it have?
It inhibits ovulation by secreting progesterone. This stops the pituitary from releasing FSH and LH.
-It thickens cervical mucous
-It effects Fallopian tube transport of the egg
It also effects the endometrium.
What differs between the newer and older POPs?
Older ones don’t inhibit ovulation.
Give an example of progesterone only pills?
Desogestel
What factors should be considered when prescribing an oral contraceptive?
Absorption- the pill is absorbed in the small intestine so diseases like crohns might mean its not as well absorbed and therefore not as effective.
Metabolism -If they are on any drugs that effect liver enzymes- the drug will be metabolised quicker.
How does the implant prevent pregnancy?
It inhibits ovulation.
Also effects the endometrium and the cervical mucous.
How do depo injections prevent pregnancy?
Inhibits ovulation
But also effects cervical mucous and the endometrium.
How long do depo injections last? How often are they changed?
14 weeks.
Changed every 13 weeks.
How does the IUS prevent pregnancy?
Has an effect on implantation- it renders the endometrium unfavourable for implantation.
It also effects the cervical mucous and has pre-fertilisation effects.
How do IUD’s prevent pregnancy?
They prevent fertilisation by being toxic to the egg and sperm joining. It causes an inflammatory response in the endometrium.
How long does the IUD last?
5-10 years.
What is the principal behind barrier contraception?
Blocks the sperm from entering the female genital tract.
What is the mode of action of female sterilisation?
Blocks the Fallopian tubes so the sperm can’t get to the egg.
What occurs in a vasectomy?
They divide the vas deferens.
What is UKMEC? What do they do?
UK medical eligibility criteria They attach a number from 1-4 to each contraceptive treatment for treatment in conjunction with diseases. Number 1- completely safe to use Number 2- benefits outweigh risks Number 3- risks outweigh benefits Number 4- absolutely do not use.
Would you do an examination before prescribing contraception?
Depends what type.
BP and BMI should be taken with all
Check smear status if relevant
If doing a coil- check uterine size and position
What do you have to make sure of before prescribing contraceptive? How would you do this?
The patient is not currently pregnant.
No sex since last period
Consistently using reliable contraception
Less than 7 days since last period
Less than 4 weeks postpartum (not breast feeding)
If breast feeding- amenorrhoeic, fully breast feeding.
Negative pregnancy test
What is the definition of quick starting contraception?
Starting contraception quickly to prevent further unprotected sex.
Which contraceptive methods can you quick start contraception with?
Some combined hormonal pills Progesterone only pills Implant Depo injection IUD
Which contraceptive methods can you not quick start?
IUS, IUD
Pills containing cyproterone acetate.
