Contraception
- Contraceptive failure is expressed by the
Non-permanent methods
Hormonal contraception
Combined oral contraceptives
- Act via negative feedback to inhibit gonadotrophin release and prevent ovulation
- Taken properly failure rate is 2 in 1000
- As well as contraception can be used for menorrhagia, premenstrual symptoms, dysmenorrhea and mild endometriosis
- Absorption can be reduced with vomiting and diarrhoea
- If liver enzyme inducing drugs are being used then the dose of oestrogen should be increased
- The pill is normally stopped 4 weeks prior to major surgery due to the prothrombotic risk
Disadvantages
- Risk of complications increased with smoking, age, obesity, diabetes, hypertension
- Thromboembolic disease
- Cardiovascular disorders
- Cerebrovascular accidents
- Associated with increased risk of CIN and cervical cancer
- Weight gain
- Nausea
- Breast tenderness
Contraindications
- History of venous thrombosis
- History of cerebrovascular or ischaemic heart disease
- Severe migraine
- Breast/endometrial cancer
- Inherited thrombophilia
- Pregnancy
- Smokers >35
- Liver disease
Progesterone-only pill
- Must be taken every day at the same time
- Inhibits tubal motility and makes cervical mucus inhospitable to sperm
- Failure rate is 1%
- Used for lactating mothers
- No increased risk of thrombosis
Disadvantages
- Breakthrough bleeding
- Weight gain
- PMT like symptoms
- Breast pain (mastalgia)
Implant contraception
- Progesterone releasing implants inserted under the skin
- Avoids first pass peak does effect in the liver
- Examples are Implanon and Norplant
- Failure rate of Implanon is 1% - lasts 3 years
- Good compliance
- Easily reversed
Disadvantages
- Disruption of the menstrual cycle – irregular periods
- Headaches
- Mood swings
- Acne
Depot injection contraception
- Depo-Provera contains medroxyprogesterone acetate (150mg)
- Injection ever 3 months
- Failure rate is 1%
- Initially there is irregular bleeding followed by amenorrhea
- Noristerat contains norethisterone an is given every 2 months
Disadvantages
- Cannot be removed so any side effects must be tolerated until it wears off
- Prolonged amenorrhea following cessation – delay in return to normal fertility of 12-18 months
- Osteoporosis risk
Post-coital contraception
- Single dose of levonorgestrel (1.5mg, Levonelle)
- Should be taken within 12hrs and no later than 72hr
- 95% successful if taken before 24hr reduced to 58% if delayed until 72hr
- Can cause vomiting and menstrual disturbances in the following cycle
Barrier Contraception
Also protect against STIs, PID and cervical cancer as well as pregnancy
Pregnancy rates vary
Condoms
- Latex sheath which fits over the erect penis
- May contain spermacide
- Failure rate of 2-15%
Diaphragm
- Thin latex rubber dome with a flexible metal spring
- Fitted across the vaginal vault before intercourse
- Must be left in place for 6-12 hours whilst the sperm are killed by the acidity of the vagina
- Additional spermacide can provide increased protection
- Increased frequency of UTIs and risk of vaginal irritation
Cap
- Held in place over the cervix by suction
- More easily dislodged during intercourse
- Similar to use as diaphragm
Intrauterine Contraception
- Placed in the uterine cavity
- Creates a sterile inflammatory reaction which prevents implantation
- Require to placed in the fundus for effectiveness
- 1 in 1000 failure rate
- Normally changed every 5-10 years
- Failure rate of 0.5%
- Two different types
- Copper containing devices – spermicidal and bactericidal. May cause pelvic pain and bleeding
- Hormone containing devices – Mirena, releases levonorgestrel (20ug/day). Used to treat menorrhagia and dysmenorrhoea
Disadvantages
- Infection
- Spontaneous expulsion
- Uterine perforation
- Ectopic pregnancy and miscarriage (if pregnancy does occur)
Natural Family Planning
- Based on observing the natural signs of the fertile and infertile periods on the menstrual cycle
- Based on
- Cervical mucus
- Cervical changes
- Basal body temperature
- Lactation amenorrhea
- Cervical mucus
- Unipath personal contraceptive device
- Measures oestradial in urine and can indicate fertile phase relating to rise in oestrdiol
Permanent Methods
Vasectomy
- Involves ligation and removal of a small segment of the vas deferens
- Sterility not assured until there has been azoospermia confirmed by 2 semen analysis
- May take up to 6 months to achieve
- Complications include, failure, post operative haematomas and infection
- Reversal is only 50% successful and can be complicated by the formation of anti-sperm antibodies
- Failure rate is similar to female sterilisation
Female sterilisation
- Performed laproscopically and involves tubal ligation with clipss
- Failure rate of 2 per 1000
- If pregnancy does occur the risk of ectopic is higher