Contraception Flashcards
What types of contraception are being used in the UK?
- sterilisation (28%)
- combined hormonal contraception (25%)
- progesterone only methods: IUD (6%), pill (5%), implants/ injectable (3%)
What are the features of the ideal contraceptive?
- reversible
- effective
- convenient and unrelated to intercourse
- no adverse side-effects
- protective against STIs
- non-contraceptive benefits
- low maintenance and no-ongoing medical input
How do contraceptive clinical trials typically report their failure rates?
By the pearl index or life table analysis
What is the pearl index?
the number of contraceptive failures per 100 women-years of exposure
- It looks at the total months or cycles of exposure from the initiation of the product to the end of the study
What is the life table analysis?
contraceptive failure rate over a specified time-frame
- can provide a cumulative failure rate for any specific length of exposure.
What form does the combined contraceptive come in?
- Pill
- Patch
- Vaginal ring
How effective is the COC?
Over 99% effective = Pearl index 0.3 - 4.0 per HWY
What does the COC contain?
It is an orally active pill combination of 2 hormones
- Ethinyl estradiol (EE)
- Synthetic progesterone (progestogen)
What is the usual dose of the COC?
Usual dose 20 – 35 microgram EE (50 if on liver enzyme inducers)
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How is the CHC usually taken?
- Taken for 21 days and then a pill free week
What is the mode of action for the CHC?
- affects FSH to LH (no surge): inhibits ovulation
- affects cervical mucus: inhibits sperm penetration
- affects endometrium: inhibits implantation
How is a surge of LH and FSH prevented when using the CHC?
Negative feedback of oestrogen and progesterone on the hypothalamus preventing LH and FSH release
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What are the non-contraceptive benefits of the COCP?
- regulates/reduces bleed - helps heavy/painful periods
- stops ovulation - helps pms
- reduction in functional ovarian cysts
- 50% reduction in ovarian and endometrial cancer
- improvement in acne/hirsutism
- reduction in benign breast disease, rheumatoid arthritis, colon cancer and osteoporosis
What are the risks associated with the COCP?
- VTE
- arterial thrombosis - MI/ischaemic stroke (increased further in those with focal migraine)
- breast cancer
- cervical cancer
What is the absolute risk of VTE contraception?
- 5 per 100,000 women years in the general population
- 15 per 100,000 women year with COC use (LNG and NET)
- 25 per 100,000 women years with COC use (GSD and DSG)
- 60 per 100,000 women years with pregnancy
What is the relative risk of VTE with COCP?
Risk increases 3 fold
What are the risk factors for VTE?
- Major surgery and immobility
- Thrombophilias
- 1st degree relative VTE under 45 years
- BMI > 30
What is the effectiveness of the progesterone only pill?
Pearl index of 0.3-3.1 = over 99% effective but it is user dependent.
Why does the POP have lower failure rates in older women?
They are less fertile and perhaps less sexually active.
Give an example of a POP?
Desogestrel pill
How is the desogestrel pill taken.?
- 12 hour window period
- Traditional pills taken within 3 hours of the same time every day without a pill-free interval