Emergency contraception (EC) is an intervention aimed at preventing unintended pregnancy after unprotected sexual intercourse (UPSI) or contraceptive failure.

The risk of pregnancy is highest 6 days preceding, and including, the day of ovulation (day 9 to day 14 of 28-day cycle).
Pregnancy, from a legal standpoint, begins at implantation (day 6 post egg fertilisation, or day 20 of 28-day cycle with mid-cycle fertilisation)

Significantly, pregnancy may already be established if >5 days after UPSI or more than day 20 of 28-day cycle with mid-cycle fertilisation.

Emergency contraception inhibits or delays ovulation or prevents sperm-egg fertilisation or prevents implantation
Emergency contraception acts prior to implantation, whereas, termination of pregnancy (abortion) acts after implantation.

Oral EC (UPA-EC, LNG-EC) is unlikely to be effective if taken after ovulation
Efficacy of oral EC improves the sooner it is taken after UPSI:
UPA-EC has a lower failure rate than LNG-EC (approx 1% vs 2%), particularly within first 12hr
Cu-IUD has the lowest failure rate (<1%).

A Cu-IUD should be offered to all women presenting up to 120 hours after first UPSI in a cycle or up to 5 days after the earliest expected day of ovulation.

Copper-intrauterine device (Cu-IUD)

<120h (5d) after first UPSI in cycle
OR >5d after UPSI but ≤5d after predicted ovulation
(in a 28d cycle, ovulation is day 14, so latest date for Cu-IUCD insertion is day 19)

Mode of action
toxic effects on ovum and sperm, preventing fertilization, anti-implantation effect

Provides immediate ongoing contraceptive protection

Rate of uterine perforation 2 per 1000 insertions

Cu-IUD is suitable for women who are breastfeeding, from 4 weeks or more postpartum

Post-partum women, particularly those breast feeding, are at slightly higher risk of uterine perforation with Cu-IUD

Ulipristal acetate UPA-EC
A selective progesterone receptor modulator

< 120 hours (5 days) of UPSI

One dose 30 mg tablet (ellaOne®)

Mode of action
Inhibit/delay ovulation

Effectiveness is reduced by concurrent liver enzyme inducers, PPIs, progestogen use (LNG-EC, CHC, HRT)

UPA-EC is contraindicated in patients with severe asthma managed with oral glucocorticoids.

Avoid breast feeding for 1 week after using UPA-EC

Quick start contraception can be started after 5 days

Levonorgestrel LNG-EC
A progestogen

< 72 hours (3 days) of UPSI

One dose 1.5 mg tablet (Levonelle®)

Mode of action
Inhibit/delay ovulation

LNG-EC can be used more than once in a menstrual cycle

Effectiveness is reduced by concurrent liver enzyme inducers and obesity.
A 3mg (double dose) should be given to women on liver-enzyme-inducers or BMI>27 (or weight>70kg)


Quick start contraception can be started immediately

Management of a woman requesting EC

1. Pregnancy should be excluded.
   A urine pregnancy test is only reliable ≥ 21 days after UPSI
   If the woman is pregnant, EC (Cu-IUCD, UPA-EC, LNG-EC) should not be prescribed.
   If (implanted) pregnancy cannot be reliably excluded and the woman wishes to take EC, use LNG-EC (off-label use).
   Cu-IUD insertion is contraindicated if (implanted) pregnancy cannot be reliably excluded.

2. Select the appropriate EC
   Consider: UK Medical Eligibility Criteria, the woman's preference, current medication, and timing of sexual intercourse.
   Advise about the efficacy, adverse effects, advantages, and disadvantages of each method.
   If vomiting occurs within 3h of taking either UPA-EC or LNG-EC, a repeat dose should be given.

3. Assess (and consider testing) for risk of STI
   Offer testing for Chlamydia trachomatis (as a minimum) before inserting the IUD; offer self-swab for chlamydia test.
   If at high-risk of chlamydia, consider using azithromycin to prevent pelvic infection, before inserting the IUD.
   Use condoms to protect against sexually transmitted infections (STIs)

4. Offer a regular method of contraception
   Regular hormonal contraception can be started at the beginning of a normal menstrual cycle.
   Alternatively, consider quick start hormonal contraception (contraception commenced at a time other than the start of a normal menstrual cycle):
   
   Quick start hormonal options after oral EC
   Quick start options: IMP, DMPA, CHC or POP
   Quick start immediately after LNG-EC, but delay for 5 days after UPA-EC (because UPA-EC interacts with progestogens).
   Additional contraceptive precautions (barrier or abstinence) are required until the quick start contraceptive method becomes effective.
   Additional contraceptive precautions: 2 days for POP and 7 days for IMP, DMPA and CHC
   

5. Follow up urine pregnancy test (UPT) in 21 days
   A urine pregnancy test is only reliable ≥ 21 days after UPSI
   UPT is recommended if experiencing abdominal pain, delayed menstruation, or irregular bleeding following EC.

Indications for emergency contraception

1. UPSI

2. Combined oral contraceptive (COC) pill (except Qlaira®) — Two or more active pills have been missed (more than 48 hours late)

3. Progestogen-only pill — Missed POP pill >3hr late (12 hours late for desogestrel-only pill)

4. Transdermal combined contraceptive patch — patch non-adherence >48hr

5. Combined contraceptive vaginal ring — Expelled for more than 3 hours

6. DMPA — more than 14 weeks since the last injection

7. Intrauterine contraception device removal — UPSI has occurred in the 5 days prior to removal, perforation, or partial or complete expulsion of the IUD/IUS

Women taking liver enzyme-inducing drugs and requesting EC

Examples of liver enzyme-inducing drugs such as St John's wort, rifampicin, phenytoin and carbamazepine, antiretroviral drugs.
Cu-IUD is the preferred option in women taking liver enzyme-inducing drugs.
Alternatively, administer double dose LNG-EC 3 mg <72 hours of UPSI.
UPA-EC is not recommended in women taking liver enzyme-inducing drugs .

Safeguarding

Consider the request for EC as a risk factor for: domestic abuse, coercive control over sex and contraceptive choices, young age and vulnerability.

In the UK, people 16 years of age and older are presumed to be competent to consent to medical treatment.
Furthermore, the legal age of consent to sexual activity is 16 years in the UK
Sexual activity under the age of consent is an offence even if consensual.
Offences are considered more serious (statutory rape) when the person is younger than 13 years of age: refer such cases to social services and the police.

In England and Wales, it is lawful to provide contraceptive advice without parental consent, provided Fraser criteria for competence are met.

Fraser competence criteria

1. The young person understands the practitioner's advice.

2. The young person cannot be persuaded to inform their parents

3. The young person is likely to begin or to continue having intercourse with or without contraceptive treatment.

4. Without contraceptive advice or treatment, the young person's physical or mental health (or both) are likely to suffer.

5. The young person's best interest requires the practitioner to give contraceptive advice or treatment (or both) without parental consent.