Emergency Contraception

Emergency contraception (EC) describes the use of contraceptive measures to prevent pregnancy occurring after intercourse has taken place.

In the UK, two forms of emergency contraception are currently recommended:

• An oral Progestogen-only Emergency Contraception (POEC) - Levonorgestrel (LNG)
• A copper Intrauterine Contraceptive Device (IUD)

Combined oestrogen and progesterone preparations were previously used, however a large randomised study showed increased effectiveness and acceptability of POEC which has now been adopted as the method of choice.¹

Mifepristone may also be used for emergency contraception but is not licensed for this use in the UK.²

Important points to note about Emergency Contraception are that:

• It is not considered an abortifactant (a Judicial Review in 2002 ruled that pregnancy begins at implantation, not at fertilization).³
• There is no time in the menstrual cycle when there is no risk of pregnancy following unprotected sexual intercourse (UPSI), particularly in an irregular cycle. Conception has been recorded as occurring on all days in a cycle, but is least likely to occur in the first three days.³
• A copper IUD is the most effective form of Emergency Contraception and should be offered to all women, even if they present within 72 hours.

When no contraception has been used

• Following consensual sexual intercourse
• Following rape or sexual assault

When there is contraceptive failure or incorrect use, including

• Incorrect use or failure of barrier methods such as the condom, diaphragm or cap
• Failed coitus interruptus (ejaculation into vagina or onto external genitalia)
• Miscalculation of the periodic abstinence method or failure to abstain during the fertile period
• IUD/IUS expulsion (if complete or partial expulsion has occurred or if it is necessary to remove the device mid-cycle and there has been UPSI within the previous 7 days)³
• Whilst using any form of hormonal contraception if intercourse has occurred whilst taking, or within 28 days after taking, enzyme inducing agents e.g. rifampicin, and if no additional barrier methods have been used.
• Following incorrect use or potential failure of hormonal method of contraception as outlined below³

Before making a shared decision with the patient as to the appropriate form of emergency contraception, a full history should be taken with particular reference to:

• Elapsed time since unprotected intercourse
• What contraception was used at the time of intercourse, if any
• Menstrual history
  • Date of LMP
  • Was the last period normal?
  • Usual cycle length
  • Is ovulation likely to have taken place yet this cycle? (If the normal cycle is 28 days, ovulation is thought to occur around day 14)
  • Could implantation of a fertilized ovum have occurred this cycle? (Implantation occurs no earlier than 5 days after ovulation.⁴ To calculate likely date of implantation subtract 14 days from the date of the expected date of the next period and add 5 days).
• Any other unprotected intercourse this cycle? Could the woman already be pregnant?
• Any previous use of emergency contraception?
• Obstetric and gynaecological history (with particular attention to history of pelvic inflammatory disease, current vaginal discharge, history of ectopic pregnancy)
• Current requirement for contraception
• Medications used, e.g. enzyme inducing agents such as phenytoin (don't forget over-the-counter enzyme inducers such as St.John's Wort)
• General health, looking for any contraindications e.g. liver disease, porphyria
• Sexual history, consider the risk of sexually transmitted infection (STI)

Mode of action

• When used early in the cycle, it is thought that POEC inhibits ovulation. When used later in the cycle, it is unclear how it has its effect.³

Prescribing

• POEC should be given in the form of levonorgestrel 1.5 mg, taken as soon as possible after UPSI
• It is now available to buy over the counter without prescription, in addition to being a prescribable drug
• Levonelle 1500® or Levonelle One Step® is a single 1.5mg dose (WHO recommended regimen)⁵

Timing of use

• Licensed for use within 72 hours of UPSI
• POEC can be used more than once in a cycle if appropriate and repeated use will not induce abortion if the woman is already pregnant. This is supported by the Faculty of Family Planning and Reproductive Health Care.³

Number of pregnancies prevented

• 84% of expected pregnancies are prevented if Levonorgestrel Emergency Contraception (LVG-EC) is used within 72 hours of UPSI. ³
• The closer to the episode of UPSI that LVG-EC is taken, the more effective it is.
• Results from a WHO trial in 1998 showed that levonorgestrel, taken as two 750 microgram doses with a 12 hour interval (the old regime), is 95% effective if taken within 24 hours of unprotected sex, 85% effective between 25 - 48 hours and 58% effective if taken between 49 - 72 hours.¹
• Some practitioners do use LVG-EC (outside it's license) between 73 and 120 hours after UPSI if an IUD is not appropriate or wanted. If used in this time scale, 63% of expected pregnancies are prevented, i.e. the failure rate rises.³
• Women who are taking enzyme inducing drugs, e.g. phenytoin, rifampicin, tropicamide, will be at risk of a higher failure rate. They should be advised that the IUD is a more reliable method for them. If they chose to take LVG-EC, they should take 2 x 1.5mg tablets as a single dose. This is outside the license for the drug and they should be informed of this.³
• No increase in dose is necessary if women are taking non-enzyme inducing antibiotics.³

Contraindications^6,7

• Hypersensitivity to levonorgestrel
• Acute porphyria
• Caution is recommended in severe liver disease
• Severe malabsorption syndromes, such as Crohn's disease, might impair the efficacy of LVG-EC
• Preparations contain lactose. Consider this in women with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption.
• Previous ectopic pregnancy is not an absolute contraindication
• POEC can be safely used during lactation
• Check INR after 3 days if concurrently taking warfarin

Side effects

• Nausea
• Vomiting

Specific advice for women using LVG-EC

• If vomiting occurs within 2 hours of taking LNG-EC, a repeat dose is needed. Re-attend or call NHS Direct if vomiting occurs (1% of women)⁸
• Use another form of contraception, e.g. condoms, for the remainder of the cycle.
• If emergency contraception is used because of missed oral contraceptive pills, women should be advised to resume their normal pill-taking regime within 12 hours of taking LNG-EC.
• There is no current evidence that POEC affects an existing pregnancy.^6,7

Mode of action

• It is thought that IUDs have an inhibitory effect on both fertilization and implantation.
• Fertilization inhibition occurs through direct toxicity effects of the copper.
• Copper can also have the effect of inhibiting sperm penetration of cervical mucus.
• Inflammatory reaction effects on the endometrium due to the copper IUD being in-situ can also prevent implantation.³
• NICE advises that the most effective IUDs have at least 380mm² of copper and have banded copper on the arms.

Timing of use

• Can be used up to 5 days after UPSI.
• If the timing of ovulation can be estimated, insertion can be beyond 5 days after UPSI, as long as insertion does not occur beyond 5 days of ovulation. ⁹
• An IUD should ideally be fitted at first presentation for emergency contraception. It may be appropriate to delay the insertion in certain circumstances, e.g. until the next-day family planning clinic service is available. In such cases, POEC should be given in the interim.

Number of pregnancies prevented

• 99% of expected pregnancies are prevented.
• It is more effective as a form of emergency contraception than POEC.

Absolute contraindications⁴

• History of copper allergy or Wilson's disease
• Past attack of bacterial endocarditis in a woman with an anatomical lesion of the heart or after prosthetic valve replacement
• Markedly distorted uterine cavity

Risk of Pelvic Inflammatory Disease (PID)

• There is a potential risk of PID when inserting an IUD in a woman who has had UPSI.
• WHO recommend that as a minimum, women at higher risk of sexually transmitted infection (age <25 years, new sexual partner or >1 sexual partner in last year) should be offered testing for chlamydia.¹⁰
• For such high-risk women, the use of prophylactic antibiotics should also be considered when the IUD is inserted.

Other points

• Previous ectopic pregnancy is not a contraindication to emergency IUD use.
• Non-copper containing IUDs (including the Mirena IUS) are not recommended for emergency contraception as there is currently no available evidence of their effectiveness.
• The IUD may be removed following the next menstrual period if not required as long term contraception.
• It may also be removed if hormonal contraception is started within the first 5 days of the next cycle.

• Discuss information about the failure rate, document this.
• Give a written advice sheet about Emergency contraception.
• Explain that their next period may be on time, early or late.
• Explain that they should return for a pregnancy test if they have not had a normal period within 7 days of their expected next period or if they have irregular bleeding.
• Advise that they should see a doctor immediately if they develop lower abdominal pain (consider the possibility of ectopic pregnancy).
• Advise about a more definitive method of contraception for the future. Written information is helpful.
• Discuss the risk of sexually transmitted infection. They have all had UPSI. They should be referred for a full sexual health screen as appropriate.
• Examine and document Fraser-ruling competence if appropriate.