Contraception and Sexual Health
UKMEC Categories
The UK Medical Eligibility Criteria grade a method against a condition, not a person against contraception in general:
| Category | Meaning | |---|---| | 1 | No restriction | | 2 | Advantages generally outweigh risks | | 3 | Risks generally outweigh advantages — needs specialist judgement, not routine use | | 4 | Unacceptable health risk — do not use |
The examinable distinction is 3 versus 4. UKMEC 3 is a conversation; UKMEC 4 is a prohibition.
Combined Hormonal Contraception — UKMEC 4 Situations
- Migraine with aura, at any age — the single most-tested item, because the risk is ischaemic stroke and it applies regardless of aura frequency
- Current breast cancer
- Under 6 weeks postpartum and breastfeeding
- Smoking ≥15/day at age ≥35
- Multiple risk factors for cardiovascular disease
- Blood pressure ≥160/100
- Current or past VTE, or known thrombogenic mutation
- Major surgery with prolonged immobilisation
- Severe (decompensated) cirrhosis, hepatocellular adenoma or carcinoma
- Systemic lupus erythematosus with positive antiphospholipid antibodies
Migraine without aura is UKMEC 2 for initiation, 3 for continuation if it develops on the pill.
Emergency Contraception
| Method | Window | Mechanism | Key limitation | |---|---|---|---| | Cu-IUD | 120 h from UPSI, or up to 5 days after earliest ovulation | Toxic to sperm and ovum; blocks implantation | Most effective by far; failure rate <1 in 1000 | | Ulipristal acetate 30 mg | 120 h | Selective progesterone receptor modulator; delays ovulation | Ineffective if LH surge has begun; progestogen within 5 days before, or 5 days after, reduces efficacy | | Levonorgestrel 1.5 mg | 72 h | Delays ovulation | Ineffective after the LH surge; double the dose if BMI >26 or weight >70 kg |
Points that recur:
- The copper IUD is the only method that works after ovulation, and the only one whose efficacy is unaffected by body weight.
- UPA and progestogen antagonise each other. Quick-starting a progestogen method after UPA means waiting 5 days, and the patient needs barrier cover in the interim.
- Enzyme-inducing drugs reduce efficacy of oral EC; the Cu-IUD is preferred, otherwise double-dose levonorgestrel.
- EC does not disrupt an established pregnancy and is not an abortifacient.
LARC
LARC is more effective than user-dependent methods because efficacy does not depend on adherence. NICE and FSRH both frame this as the reason to offer it first.
| Method | Duration | Notes | |---|---|---| | Cu-IUD | 5–10 y depending on device | Non-hormonal; heavier, more painful periods | | LNG-IUS 52 mg | 8 y contraception; 5 y for endometrial protection with HRT | Also licensed for heavy menstrual bleeding | | LNG-IUS 13.5/19.5 mg | 3–5 y | Smaller frame, lower systemic dose | | Implant (etonogestrel) | 3 y | Most effective reversible method; unpredictable bleeding is the commonest reason for removal | | DMPA injection | 13 weeks | Delayed return of fertility (up to a year); reversible reduction in bone mineral density |
IUD insertion risks to quote: uterine perforation ~1–2 per 1000 (higher when breastfeeding), expulsion ~1 in 20 (commonest in the first year, especially the first 3 months), and PID risk raised only in the first 20 days after insertion. Failure carries an increased proportion of ectopic pregnancies, though the absolute ectopic risk is lower than using no contraception at all — a distinction worth stating precisely.
Missed Pills and Quick Start
- COC: one missed pill (≤48 h since last) — take it and continue, no extra precautions. Two or more — take the most recent, use condoms for 7 days, and consider EC if unprotected sex occurred in the pill-free interval or week 1.
- POP (desogestrel): 12-hour window. Traditional POP: 3 hours.
- Quick start is appropriate whenever pregnancy can be reasonably excluded; it avoids losing the patient to a delayed start.
Contraception in Specific Situations
- Postpartum: contraception is needed from day 21. Progestogen-only methods and implants can start immediately, including while breastfeeding. CHC is UKMEC 4 before 6 weeks if breastfeeding.
- Post-abortion: all methods, including IUD, can start immediately.
- Perimenopause: contraception until 55, or 2 years of amenorrhoea under 50, 1 year over 50. The LNG-IUS provides endometrial protection alongside oestrogen HRT.
- Bariatric surgery: oral contraceptive absorption may be reduced after malabsorptive procedures.
High-Yield Exam Points
- Migraine with aura is UKMEC 4 for combined hormonal contraception at any age. Without aura it is 2 to start.
- Ulipristal and progestogens interfere with each other in both directions.
- Double-dose levonorgestrel above 70 kg or BMI 26; the copper coil is unaffected by weight.
- IUD-related PID risk is confined to the first 20 days after insertion.
- DMPA reduces bone mineral density reversibly — relevant in adolescents and approaching menopause, not a reason to withhold it from most users.
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