What is the mode of action of the combined oral contraceptive pill?
- Suppresses ovulation.
- Reduces sperm pentrability of cervical mucus.
- Alters endometrium to reduce the likelihood of implantation.
What to do in the event of a missed pill?
- It takes 7 consecutive pills to ensure that ovulation has been suppressed.
- Follicular activity can begin to return towards the end of the 7 day break, therefore avoid lengthening the ‘sugar pill’ period beyond 7 days.
- If greater than 12 hours late with 1 or more pills then take today’s pill as soon as possible.
- Consider emergency contraception.
- Use additional measures such as condoms for 7 days.
- If there are less than 7 pills left then continue straight on with the next packet and omit the pill-free week.
What are the considerations for the combined oral contraceptive pill and women approaching menopause?
- The COCP will mask the menopause due to normal levels of oestrogen and regular bleeds. This effect disappears after 6 weeks.
- If COCP is stopped before age of 50, presume loss of fertility after 2 years of amenorrhoea.
- If COCP is stopper after age of 50, presume loss of fertility after just 1 year of amenorrhoea.
What are the advantages and disadvantages of the combined oral contraceptive pill?
ADVANTAGES
DISADVANTAGES
- high efficacy (failure rate of 0.1 to 3 per 100 woman years)
- reversible (may be a delay of up to 1 year)
- not related to intercourse
- reduced menstrual blood flow
- reduced dysmenorrhoea
- increased predictability of menses
- reduced PMS
- reduced PID
- reduced ectopic pregnancy
- reduced benign breast disease
- reduced ovarian cancer
- reduced endometrial cancer
- reduced functional ovarian cysts
- increased cardiovascular morbidity (VTE, IHD, CVA, HT)
- increased breast cancer
- increased cervical cancer
- increased liver adenomas
- cholestasis
- gallstones
What is the significant of migraine with aura in regards to the combined oral contraceptive pill?
- Increases the risk of ischaemic stroke.
When should the Depo-Provera be commenced?
- Day 1 to 5 of the menstrual cycle.
- Day of abortion or miscarriage.
- 6 weeks postpartum.
- Day of last pill of POP/COCP if switching.
What is the mechanism of action of the Depo-Provera?
- Progesterone-only.
- Suppresses the hypothalamopituitary axis resulting in consistent inhibition of ovulation.
- Reduced oestrogen levels compared to the POP, Implanon and Mirena.
What are the advantages and disadvantages of injectable progesterones (eg. Depo-Provera)?
ADVANTAGES
DISADVANTAGES
- good for poorly compliant or travelling patients
- improves endometriosis
- improves dysmenorrhoea
- improves menorrhagia
- reduces iron deficiency anaemia
- improves PMS
- reduces epileptic seizures
- no CVS effects (eg. HT, IHD, CVA, VTE)
- menstrual disturbance (amenorrhoea in the long term)
- headaches and dizziness (3-19%)
- breast tenderness
- mood changes
- depression
- weigh gain (2kg in first year)
- delay in return of fertility (70% conceive in the first year)
- reduced oestrogen levels (?adverse effect on bone density)
- small risk of breast cancer (similar to COCP)
What is the mechanism of action of the progesterone implant (eg. Implanon)?
- Inhibits ovulation by preventing the LH surge.
- Blockade of cervical mucus.
- Suppression of oestrogen-induced cyclical maturation of endometrium.
- Endogenous oestrogen is synthesised normally.
When is the appropriate time to insert an Implanon?
- Day 1 to 5 of cycle.
- Can be inserted immediately postpartum.
What are the advantages and disadvantages of the Implanon?
ADVANTAGES
DISADVANTAGES
- rapid return of ovulation on removal
- 2 year continuation rate is 69%
- no increased risk of CVS or VTE problems
- variable bleeding pattern
- headaches
- acne
- breast pain
- weight gain
- chloasma
What is the mechanism of action of the levonorgestral intrauterine system (eg. Mirena)?
- Mirena results in profound endometrial atrophy, decidualisation and foreign body reaction.
- Changes in cervical mucus.
- Ovulation is not suppressed.
When should the Mirena be inserted?
- Before day 7.
What are the advantages and disadvantages of the Mirena?
ADVANTAGES
DISADVANTAGES
- safe
- highly effective
- long-acting
- failure rate is 0.3 per 100 women years
- no delay in return of fertility on removal
- insert before day 7
- risk of perforation 1 in 1000
- risk of expulsion 5 per 100 women years
- incidence of ectopic pregnancy 0.02 per 100 women years
What is the effect of progestogen-only injectables on bone mineral density?
- There appears to be an initial small loss of bone density that returns when DMPA is discontinued.
- Those women on DMPA suffer an initial loss of bone density but, unlike other women, menopause does not incur further loss in bone strength.
