Contraception
Contraception encompasses the range of methods used to prevent pregnancy, with NICE and FSRH guidance supporting patient-centred choice across hormonal, non-hormonal, and permanent options.
Key Facts
Long-acting reversible contraception (LARC) is most effective and cost-effective (NICE CG30): includes IUD, IUS, implant, and injectable Nexplanon (etonogestrel implant): >99.9% effective, lasts 3 years Mirena IUS (LNG 52mg): >99% effective, lasts 5 years (also licensed for HRT and menorrhagia) Copper IUD: >99% effective, lasts 5-10 years depending on device; also the most effective emergency contraception UKMEC categories classify contraindication risk: Category 1 (no restriction), 2 (benefits>risks), 3 (risks>benefits), 4 (unacceptable risk) COC pill is UKMEC 4 with migraine with aura, current breast cancer, >35 years and smoking >15/day, or <6 weeks postpartum if breastfeeding Quick start of contraception is recommended by FSRH: start any method at any time in the cycle with appropriate precautions Perfect use failure rates differ from typical use: COC 0.3% vs 9%; condoms 2% vs 18%
Overview
Key Facts
Contraception is a fundamental aspect of reproductive healthcare. The wide range of available methods allows individualised choice based on efficacy, side effects, non-contraceptive benefits, and patient preference. NICE and FSRH guidelines support promoting long-acting reversible contraception (LARC) as the most effective option.
Epidemiology
- Approximately 75% of women of reproductive age in the UK use some form of contraception
- Most commonly used methods: COC pill (25%), condoms (25%), LARC (15-20%)
- Unintended pregnancy rate: approximately 16% of pregnancies in the UK
- LARC use has been increasing following NICE CG30 recommendations
Aetiology
- Not applicable (preventive medicine)
Pathophysiology
- Hormonal methods work by: suppressing ovulation (COC, POP, implant, injectable), thickening cervical mucus (all progesterone-containing), thinning endometrium
- Copper IUD: toxic to sperm and ova; prevents fertilisation and implantation
- Barrier methods: physical prevention of sperm reaching the ovum
- Sterilisation: permanent occlusion of fallopian tubes or vas deferens
Clinical Presentation
Consultation Approach
- Assess patient's priorities: efficacy, convenience, side effects, reversibility, non-contraceptive benefits
- Sexual health history and STI risk assessment
- Medical history and UKMEC categorisation
- Reproductive plans and fertility wishes
When to Suspect Contraceptive Failure
- Missed period or irregular bleeding with suboptimal use
- Pregnancy symptoms
- Displaced or expelled IUD/IUS
Red Flags
- Pregnancy with IUCD/IUS in situ (risk of ectopic, miscarriage, sepsis)
- Symptoms of ectopic pregnancy with any contraceptive failure
- Signs of VTE with hormonal contraception use (leg swelling, chest pain, dyspnoea)
Differential Diagnosis
| Diagnosis | Key Features | Investigation |
|---|---|---|
| Pregnancy (contraceptive failure) | Amenorrhoea, nausea, breast tenderness | Urine/serum βhCG |
| Ectopic pregnancy | Unilateral pain, PV bleeding, positive pregnancy test | TVS, serial βhCG |
| Hormonal side effects | Irregular bleeding, mood changes, headache | Clinical assessment |
| STI | Vaginal discharge, pelvic pain, dyspareunia | STI screen |
Diagnosis / Investigation
Bedside
- Blood pressure (before combined hormonal contraception)
- BMI
- Pregnancy test (if pregnancy cannot be excluded)
- STI screening if indicated
Bloods
- Not routinely required for contraception initiation
- Consider FBC if heavy menstrual bleeding
- Lipid profile and glucose if cardiovascular risk factors (before COC)
Imaging
- Pelvic USS: if IUD/IUS malposition suspected (missing threads)
- TVS: to confirm IUD/IUS position
Special Tests
- Chlamydia screening recommended for under 25s or new sexual partner before IUD/IUS insertion
- Cervical screening as per national programme (not specifically related to contraception choice)
Management
Non-pharmacological
- Condoms (male/female): barrier method; also protects against STIs; typical use failure rate 18%
- Natural family planning: fertility awareness methods; typical use failure rate 24%
- Male sterilisation (vasectomy): permanent; failure rate <0.05% after confirmed azoospermia
- Female sterilisation: laparoscopic tubal occlusion; lifetime failure rate 1 in 200
Pharmacological
- Combined oral contraceptive (COC): ethinylestradiol 20-35mcg + progestogen; 99.7% effective (perfect use)
- Progesterone-only pill (POP): desogestrel 75mcg OD (Cerazette); 12-hour window (vs traditional 3-hour POP)
- Combined patch (Evra): weekly application for 3 weeks, 1 week off
- Combined vaginal ring (NuvaRing): inserted for 3 weeks, removed for 1 week
- Nexplanon (etonogestrel implant): subdermal, 3 years, >99.9% effective
- Depo-Provera (medroxyprogesterone acetate 150mg IM): every 12 weeks; consider bone density effects if used >2 years (FSRH)
- Mirena IUS (LNG 52mg): 5 years; also treats menorrhagia; licensed for endometrial protection in HRT
- Copper IUD: non-hormonal, 5-10 years; most effective emergency contraception up to 5 days
Surgical/Interventional
- IUD/IUS insertion: outpatient procedure; requires trained provider
- Nexplanon insertion: subdermal in non-dominant upper arm
- Laparoscopic sterilisation: day-case procedure; counsel regarding permanence and failure rate
Referral Criteria
- Complex medical conditions (UKMEC 3/4): specialist contraceptive clinic
- Failed IUD/IUS insertion: referral for USS-guided insertion
- Request for sterilisation: counselling and informed consent process
- Post-bariatric surgery: specialist advice on absorption issues
Prognosis
- LARC methods have the highest continuation rates and user satisfaction
- Fertility returns immediately after removal of implant, IUD, IUS, or stopping COC/POP
- Depo-Provera: return to fertility may be delayed by 6-12 months (average)
- Sterilisation reversal: success rates vary (40-80%); IVF may be more reliable alternative
- Long-term COC use: associated with small increased risk of breast cancer (RR 1.24) but reduced risk of ovarian and endometrial cancer
Other Relevant Information
Contraceptive Efficacy Comparison
| Method | Perfect Use (%) | Typical Use (%) | Duration |
|---|---|---|---|
| Nexplanon | 99.95 | 99.95 | 3 years |
| Mirena IUS | 99.8 | 99.8 | 5 years |
| Copper IUD | 99.4 | 99.2 | 5-10 years |
| Depo-Provera | 99.8 | 96 | 12 weeks |
| COC pill | 99.7 | 91 | Daily |
| POP (desogestrel) | 99.7 | 91 | Daily |
| Male condom | 98 | 82 | Per use |
| Female sterilisation | 99.5 | 99.5 | Permanent |
UKMEC Category 4 Conditions for COC
| Condition | Rationale |
|---|---|
| Migraine with aura | Increased stroke risk |
| Current breast cancer | Hormone-sensitive tumour |
| >35 years + smoking >15/day | Cardiovascular risk |
| <6 weeks postpartum + breastfeeding | Oestrogen effect on milk |
| History of VTE | Thrombotic risk |
| Known thrombophilia | Thrombotic risk |