contraception Flashcards
which hormones have a negative feedback effect on the hypothalamus
oestrogen and progesterone
which hormones have a negative feedback effect on the pituitary gland
oestrogen and progesterone
which hormones are involved in the hypothalamic-pituitary-ovarian axis
GnRH
LH and FSH
oestrogen and progesterone
how long can sperm survive in the female genital tract
5 days
how long do ovum survive in the female genital tract
up to 24 hours
what is the pearl index and how is it calculated
it represents the number of contraceptive failures per 100 women users/year
(no. of accidental pregnancies x 1200)/total number of months of exposure
what are some methods of using natural family planning as contraception
basal body temperature cervical position cervical mucous 'standard' days breast feeding
how is basal body temperature measured and how is it affected by fertility
taken before rising every morning
increase in body temp >0.2 degrees post ovulation
increase in temp sustained for 3 days
increase in temp follows at least 6 days of lowered temperature
how can changes to cervical mucous predict ovulation
thick and sticky post ovulation (3 days)
then become thinner, watery, ‘stretchy’
how does cervical position indicate fertility
when fertile the cervix is high in the vagina, soft and open
when less fertile it is low, firm and closed
what are ‘standard’ days
in a regular 28 day cycle, days 8 to 18 are most fertile
what are the criteria for lactational amenorrhoea
exclusively breast feeding
less than 6/12 post natal
amenorrhoeic
which hormones are present in combined hormonal contraception
oestrogen and progesterone
mode of action of combined hormonal contraception
primarily inhibits ovulation
effect on cervical mucous
effect on endometrium
mode of action of newer POP
inhibits ovulation
effects on cervical mucous
effects on Fallopian tube transport
effects on endometrium
mode of action of older POP
effects on cervical mucous
effects on Fallopian tube transport
effects on endometrium
which factors can affect the efficacy of CHC and POP
absorption
metabolism
what is LARC
long acting reversible contraception
mode of action of the implant
inhibition of ovulation
effect on endometrium
effect on cervical mucous
mode of action of depo injection
inhibits ovulation
effect on cervical mucous
effect on endometrium
mode of action of IUS
effect on implantation (endometrium rendered unfavourable for implantation)
also effect on cervical mucous and pre-fertilisation effects
what are the 3 doses of IUS currently available
mirena 52 mg
kyleena 19.5 mg
jayvees 13.5 mg
mode of action of IUD
prevention of fertilisation
inflammatory response in endometrium
mode of action of female sterilisation
blocs the Fallopian tubes (filshie clips)
why must there be no risk of pregnancy before female sterilisation
high risk of ectopic pregnancy
what is UKMEC 1
no restriction for the use of contraceptive method
what is UKMEC 2
advantages outweigh the risks
what is UKMEC 3
risks outweigh the advantages, requires expert clinical judgement
what is UKMEC 4
unacceptable risk
what baseline examination is done before prescribing contraception
BP and BMI
what risk factors should be considered before prescribing contraception
osteoporosis
CV disease
breast cancer
VTE
what are the criteria to be ‘reasonably certain’ you’re not pregnant
no sex since last period
consistently using reliable contraception
<7 days since last normal period
<4 weeks post party (not breast feeding)
lactational amenorrhoea
negative pregnancy tests AND >3 weeks since UPSI
what is quick-starting contraception
starting contraception when patient presents ie not waiting until next period
which contraception can be used for quick start
some CHC
POP
implant
depo
what is bridging contraception
when the preferred method of contraception can’t be started immediately because pregnancy cannot be excluded and an interim method is used
when might emergency contraception be needed
when contraception hasn’t been used
when contraception hasn’t been used properly
before new contraceptive method has had chance to become effective
when is the highest risk of pregnancy
30% risk during 5 days before plus day of ovulation
indications of EC
up to 5 days after UPSI
within 5 days of predicted ovulation
methods of EC
copper IUD
LNG-EC
UPA-EC
how long is LNG-EC effective
up to 72 hours post UPSI
how long is UPA-EC effective
up t 120 hours post UPSI
what is the most effective form of EC
IUD
how does oral EC work
UPA = anti-progestogen
LNG = high dose progestogen
DELAY OVULATION
when is oral EC likely to be effective
LNG-EC works until just before LH surge
UPA-EC can work during LH surge but not after peak
neither work after ovulation
when to avoid UPA
if wishing to ‘quick-start’ hormonal contraception
must delay ongoing contraception for 5 days
if hormonal contraception has been used in past 7 days
if patient has acute severe asthma uncontrolled by oral steroids
non-contraceptive benefits of contraception
heavy menstrual bleeding painful periods irregular periods premenstrual symptoms endometriosis menstrual migraine (no aura)
what is scheduled bleeding
menstruation or regular withdrawal bleeding with CHC
what is the failure rate of CHC with typical use
9%
what are tailored regimens
off licence uses of COC, generally to prevent withdrawal bleeding
types of tailored regimes
tai-cycling (taking 3 packs back to back then 4-7 days off) shortened hormone free interval (3/52 on, then 4/7 off) extended use (use continuously until breakthrough bleeding, then stop of 4-7 days)
what are the main risks of CHC
venous thrombosis
arterial thrombosis
adverse effects on some cancers
how high is the the risk of VTE in users of COC
low but will affect individuals with other risk factors for VTE
UKMEC risk factors for VTE
obesity smoking age known thrombophilia VTE in first degree relative <45 years up to 6 weeks post natal
non-UKMEC risk factors for VTE
trekking >4,500 m for >1 week
long haul flights
reduced mobility
APS
what is the VTE risk in pregnancy per 10,000 women
12-20
what is the VTE risk on the first weeks post-natally per 10,000 women
300-400
what is cyprterone acetate used to treat
acne and hirsutism
why is CHC contraindicated in patients with migraine with aura
increases the risk of ischaemic stroke
breast cancer and UKMEC criteria
personal history - CHC contraindicated
family history - UKMEC 1
BRACA - UKMEC 3
risk factors to consider when prescribing CHC
smoking obesity age HTN diabetes with vascular complications postnatal vascular disease immobility FHx of VTE APS trekking at altitudes breastfeeding
risks of IUS and IUD
procedure infection perforation expulsion failure risk to pregnancy when in situ
complications of vasectomy
anaesthetic pain infection bleeding/haematoma failure
