Contraception - emergency
Exam Tips
- For UK exams: Cu-IUD is first-line most effective EC and is the only option still effective after ovulation.
- Ulipristal can be used up to 120 hours; levonorgestrel is licensed to 72 hours (unlicensed 72-96 hours with lower efficacy).
- If vomiting occurs within 3 hours of oral EC, repeat the dose.
- Oral EC does not cover further UPSI in the same cycle; advise condoms/abstinence and ongoing contraception.
- Always arrange a pregnancy test 3 weeks after the last UPSI and safety-net for ectopic symptoms.
- Remember key interaction: enzyme inducers reduce oral EC efficacy; recent or early progestogen use reduces ulipristal effectiveness.
Definition
Emergency contraception is a time-sensitive intervention used after unprotected sexual intercourse (UPSI) or contraceptive failure to reduce the chance of pregnancy. In UK practice, options are the copper intrauterine device (Cu-IUD), oral ulipristal acetate, and oral levonorgestrel; these act before implantation and are not abortifacients.
Pathophysiology
Sperm can remain viable in the female genital tract for up to about 5 days, so pregnancy risk depends on whether ovulation occurs in that window. Levonorgestrel mainly works before the luteinizing hormone (LH) surge by delaying ovulation; ulipristal acetate can still delay follicular rupture closer to ovulation (including early LH rise), but neither oral method is reliably effective after ovulation. A Cu-IUD is most effective because copper impairs sperm and ovum function and creates a local endometrial inflammatory environment that prevents implantation if fertilization occurs. See Figure: menstrual cycle timing of LH surge and fertile window.
Risk Factors
- Unprotected vaginal intercourse at any cycle point when pregnancy is not desired
- Contraceptive failure (for example condom break/slip, missed pills, delayed injection, patch/ring errors)
- Multiple episodes of UPSI in the same cycle
- Postpartum from day 21 if lactational amenorrhoea method criteria are not fully met
- From day 5 after miscarriage, abortion, ectopic pregnancy, or uterine evacuation for gestational trophoblastic disease
- Use of liver enzyme-inducing medicines reducing oral EC effectiveness
- Higher body weight/BMI (reduced efficacy concern for levonorgestrel)
Clinical Features
Symptoms
- History of recent UPSI or contraceptive mishap
- Anxiety about unintended pregnancy
- Possible lower abdominal discomfort or nausea (often unrelated to EC efficacy)
Signs
- Usually no abnormal physical signs
- May require pelvic assessment only if Cu-IUD is being considered or symptoms suggest alternative pathology
- Safeguarding or coercion indicators in younger or vulnerable patients
Investigations
Management
Lifestyle Modifications
- Provide confidential, non-judgemental counselling; assess Fraser competence and safeguarding if <16 years
- Advise abstinence or consistent condom use for the rest of the cycle after oral EC
- Discuss and start/arrange reliable ongoing contraception promptly
- Safety-net: perform pregnancy test at 3 weeks after last UPSI and seek urgent review for pain/bleeding (ectopic red flags)
- Offer STI risk assessment, testing, and vaccination/prophylaxis as appropriate
Pharmacological Treatment
Selective progesterone receptor modulator (oral EC)
- Ulipristal acetate 30 mg orally as a single dose within 120 hours of UPSI
More effective than levonorgestrel near ovulation; repeat the same dose if vomiting occurs within 3 hours. Avoid with liver enzyme-inducing drugs and avoid starting progestogen for 5 days after dose; efficacy may be reduced if progestogen was taken in previous 7 days. Not for use once ovulation has passed.
Progestogen (oral EC)
- Levonorgestrel 1.5 mg orally as a single dose within 72 hours of UPSI (can be used 72-96 hours unlicensed, with reduced efficacy)
Repeat 1.5 mg if vomiting within 3 hours. Less effective close to/after LH surge and after ovulation; ineffective beyond 96 hours. Reduced effectiveness with enzyme-inducing drugs and in higher BMI/weight; consider Cu-IUD when suitable.
Surgical / Interventional
- Copper intrauterine device insertion for EC by a trained clinician: insert within 120 hours of first UPSI in cycle or within 120 hours of earliest estimated ovulation (whichever is later); may be retained for ongoing contraception
- Counsel on insertion risks: pain, unscheduled bleeding, expulsion, infection risk, and rare uterine perforation (higher perforation risk during lactation); does not protect against STIs
Complications
- Unintended intrauterine pregnancy if EC fails or is delayed
- Ectopic pregnancy (must be considered if pain/bleeding after EC or positive test)
- Adverse effects of oral EC: nausea, vomiting, headache, dizziness, mood change, lower abdominal pain
- Cu-IUD-related complications: insertion pain, heavier/irregular bleeding, expulsion, uterine perforation, pelvic infection
Prognosis
Excellent when EC is used promptly and appropriately. Cu-IUD has the highest effectiveness (pregnancy rate <0.1%), while oral methods are less effective and timing-dependent (ulipristal roughly 1-2%; levonorgestrel around 0.6-2.6% within 72 hours), so delay and cycle timing worsen outcomes.
Sources & References
✅NICE Guidelines(1)
- Contraception - emergency[overview]