FFinalistSouthampton · 2027
Obstetrics & gynaecology
AKT · Obstetrics & gynaecology/Contraception

Emergency contraception

Copper IUD · ulipristal acetate · levonorgestrel

Overview

Prevents pregnancy after unprotected sex (UPSI) or contraceptive failure. Three options with different windows and mechanisms — the copper IUD is by far the most effective and the only one that works after ovulation; the oral methods only delay ovulation.

Recognise

  • Copper IUD: most effective; within 120h (5 days) of UPSI or 5 days of expected ovulation; works post-ovulation
  • Ulipristal acetate 30mg (ellaOne): within 120h; delays ovulation; more effective than levonorgestrel mid-cycle
  • Levonorgestrel 1.5mg: within 72h; only effective BEFORE ovulation (double the dose if BMI >26 / >70kg or enzyme inducers)

Red flags

  • Exclude an existing pregnancy/late presentation; severe asthma on oral steroids cautions ulipristal; safeguarding if under-age

Differentials & how to tell them apart

Levonorgestrel oral EConly within 72h and only before ovulation — least effective mid/late cycle
Ulipristal oral ECwithin 120h, more effective mid-cycle, but delays starting hormonal contraception by 5 days
Copper IUDmost effective, the only one effective after ovulation, gives ongoing cover

Investigations

Cycle timing and time since UPSI (decides which option); pregnancy risk assessment; discuss ongoing contraception.

Management

Offer the copper IUD first (most effective); otherwise ulipristal (≤120h) or levonorgestrel (≤72h)

  1. 1Offer the copper IUD first-line (most effective, works post-ovulation, ongoing cover).Gate: If the IUD is declined/unavailable: ulipristal within 120h, or levonorgestrel within 72h — levonorgestrel does NOT work once ovulation has occurred
  2. 2Quick-start ongoing contraception: immediately after levonorgestrel; WAIT 5 days after ulipristal (it antagonises progestogens). Pregnancy test if next period is late/light.
Ulipristal acetate 30mg — selective progesterone receptor modulator; avoid breastfeeding 1 week; delays starting hormonal contraception 5 days
Levonorgestrel 1.5mg (3mg if BMI>26/enzyme inducers) — progestogen; can start hormonal contraception immediately after
Copper IUD — most effective; insert within the window

Key points

Ulipristal and progestogen contraception interact — ulipristal efficacy is reduced and it delays starting/continuing hormonal contraception by 5 days. Enzyme inducers: prefer the copper IUD or double-dose levonorgestrel.

Monitor & prognosis

Pregnancy test if period >5–7 days late; arrange ongoing contraception + STI screen.

Effective; failure rises the later it is taken (oral) or near ovulation.

Source: FSRH Emergency Contraception guideline (2023)