Contraception Flashcards
If it existed, what would be the characteristics of a perfect contraceptive?
- 100% effective
- Safe and reversible
- Independent of intercourse
- Cheap/free
- Non-invasive
- Acceptable to all religions/cultures
- Prevent STIs
How is the efficacy of contraception measured?
- Pearl Index - risk of pregnancy per 100 woman years of using contraceptive method
- Eg if PI = 2, of 100 woman using it for a year, two will get pregnant by the end
- Users compliance - user dependent contraceptives eg pills/condoms - perfect use > typical use
What is contraception?
Prevention of pregnancy
When does pregnancy occur?
When implantation occurs
What are the risks of pregnancy?
- Sperm survival ( can survive up to 7 days)
- Only 30% of females are fertile in fertile window
What are the long acting forms of contraceptives? How long does each last?
- Injectables (3 months)
- Implants (3yrs)
- Intrauterine system (IUS)/devices (IUD) (5 yrs)
What are the two broad types of contraception?
- Hormonal
- Non-hormonal
Name the non-hormonal methods of contraception
- Intrauterine devices (IUD)
- Sterilisation
- Barrier methods
- Natural methods
- Withdrawal
What are the hormonal methods of contraction?
- Implants
- Intrauterine system (IUS - Mirena)
- Injectables
- Pills
- Patches
- Vaginal Rings
- Emergency contraception
What are the UK MEC criteria for contraception?
- 1: No restriction (A = always)
- 2: Advantages outweigh risks (B = Benefits outweigh risk)
- 3: Risks outweigh advantages (requires expert judgement or referral to specialist) (C = use with caution)
- 4: Unacceptable health risk (D = Don’t even think about it!)
What do patients want to know about contraceptives?
- Side effects - bleeding, weight, pain
- Risks? - future fertility How effective it it How does it work?
What do health care professions want to know about patients who want contraceptives?
- Whats the patient choice
- Dangerous patients
- Compliance - Method/user failure, understanding
What do all combined contraceptive pills contain? What are the exceptions?
- Synthetic Oestrogen (ethinyl oestradiol) -
- Progestogen
EXCEPT
- Qlaira and Zoely contain oestrodiol valerate (metabolised in body to naturally occurring oestrodiol)
- Mestranol in Norinyl-1
How do COC work?
ANOVULANT
- Osterogen has negative feedback on FSH (follicles do not develop)
- Progestogen has negative feedback on LH (no ovulation)
- Also causes endometrial atrophy and thickens cervical mucus
How often is the COC taken?
One active pill is taken daily for 21 days out of every 28 (3 weeks on, 1 week off)
What happens once the patient has finished the pill packet by the end of week 3?
- Withdrawal bleed - reduced progestogen stimulus on endometrium
- The cycle is then restarted
What do ‘everyday’ pills contain? What is their advantage?
- Taken everyday without a break - but have 7 inactive pills
- Aids compliance
If not everyday preperations, what is week where there are no pills taken referred to as?
PFI (pill free interval)
What preperations do most COC come in as? What does this mean? How do others come as?
- Monophasic pills - delivers same dose of oestrogen and progesterone everyday.
- 21 pills (3 weeks on, one week off)
- Diphasic and monophasic - vary the dose throughout the pack, in two or three phases
What is the dose that most COCs come as? (ethinyloestradiol)
- Ethinyloestradiol - 20µg (low dose), 30µg or 35µg (standard dose)
- e.g. microgynon 30
How many generations of progestogens are there? WHat progestogens belong in each generation?
- 1st generation - Norethisterone
- 2nd generation - norgestrel, levonorgestrel
- 3rd Generation - Gestodene, Desogestrel, Norgestimate
- 4th Generation - Drospirenone, Dienogest
What type of progestogen is used in the most common COC brand (Microgynon 30 )?
- levonorgestrel
How do newer generations of progestogens compare to older protestogens?
- Have less androgenic side effects
- Newer the progestogen, the more expensive the pill tends to be
- Slight increase in risk of VTE - not clinically important!
Which characteristic of the COC pill determine bleeding patterns the most? Progestogen type, oestrogen dose or type of phasic regime?
- Progestogen type
What is the efficacy of COC preperations (PI)? How is COC efficacy affected?
- Perfect: PI = 0.1 per 100 woman years
- Typical Use = 5%
- Failure rate of 1% = 30,000 unplanned pregnancies
- Low dose (20 mcg) and standard dose (30, 35 mcg) = similar efficacy
- However small margin for error
- I.e. doses only sufficient to prevent ovulation in some women
What are the indications for COC use?
- Contraception - ‘from menarche (+ condoms) to menopause’ (40 yrs old without CV RFs)
- Menstrual cycle control
- Menorrhagia
- Premenstrual syndrome
- Dysmenorrhoea
- Acne/hirsutism
- Prevention of recurrent cyts
What patients are given COC becauser the beenfits outweight the risk?
- >40+
- Smoking - <35yrs
- Obesity - BMI >30
- Hx of ↑BP in pregnancy
- Major surgery without immbolisation
- Superficial thrombophlebitis
- Uncomplicated valvular disease
- Non-focal migraine and <35 yrs
- Asymptomatic gallbladder disease
- Uncomplicated DM
- Hyperlipidaemia
- VTE in 1st degree (<45yrs, check thrombophilia screen)
- Undiagnosed Breast, CIN or Cervical Cancer
- Sickle cell disease
What patients should the COC pill be cautioned in (Category 3: risks outweigh benefits)?
- Age >40yrs
- Postpartum <21 days
- Smokers: <15 cigs and >35 yrs
- Hypertension: ( 140/90 - 159/99)
- Non-focal migraine and >35yrs
- Hx of breast cancer
- Gallbladder disease (symptomatic or on medical Tx)
- Cirrhosis (mild compensated)
- Taking enzyme inducers
- Breastfeeding (<6 months post-partum) - suppresses lactation
What patients are COC completely CI in? (category 4 - absolulte contraindication)
- Current or Hx of VTE
- Smokers: >15 cigs and >35 yrs (↑ VTE risk)
- Breastfeeding <6 weeks postpartum
- BMI > 40
- Focal migraine (with aura)
- Hx of CVA, IHD, Valvular heart disease
- Multiple risk factors for Arterial CV
- Severe hypertension (>160/100)
- Pregnancy (↑ VTE risk)
- Major surgery with immoblisation (stop at least 4 weeks before)
- Active breast/endometrial Cancer - oestrogen dep
- Inherited thrombophilia
- DM with vascular complications
- Active/chronic liver disease