Emergency contraception is a useful means of preventing unplanned pregnancy after unprotected sexual contact or potential contraceptive failure (see Table Indications for emergency contraception). Although pregnancy is unlikely before day 7 of the cycle or after day 17 of the cycle in a woman with a 28-day cycle, any request for emergency contraception should be assessed for risk based on Table Indications for emergency contraception and — if indicated — emergency contraception offered.

Table Indications for emergency contraception

Unprotected sex (consensual or non-consensual)

(1) Intercourse where contraceptive method was not used or used incorrectly

(2) Coitus interruptus

(3) After rape or sexual assault

(4) Ejaculation on to external genitalia

Potential contraceptive failure

(1) COCs

(a) two or more pills missed from first seven of the pack

(b) four or more pills missed mid-pack

(c) potential drug interaction

(2) POPs

(a) one or more pills missed (taken more than 3 h late)

(b) potential drug interaction

(3) IUDs

(a) expulsion (partial or complete)

(b) mid-cycle removal after intercourse in previous seven days

(4) Barriers

(a) condom split, slippage or incorrect use

(b) diaphragm split, displacement or incorrect use

COC, combined oral contraceptive, POP, progestogen-only pill; IUD, intrauterine device

Whilst having been demonstrated to be effective if commenced any time up to 72 h after sex, the efficacy of the hormonal methods (Levonelle-2 and Schering PC4) declines with time after intercourse. Because of this, a request for emergency contraception should — wherever possible — be dealt with at the time of the request. On-call services and accident and emergency departments are therefore important points for accessing emergency contraception. Furthermore, Levonelle-2 can be bought over the counter for emergency use. Good access to emergency IUDs is important, and all services offering hormonal methods should have access, by referral if necessary, to this method.

Efficacy of emergency contraception

The efficacy of emergency contraception can be expressed either as the chance of pregnancy after using the method, or as the ratio of observed to expected pregnancies. The latter is used in this text.

Methods of emergency contraception

There are three main methods of emergency contraception: two hormonal and one intrauterine.

Progestogen-only hormonal emergency contraceptives

Licensed in 1999, Levonelle-2 is the most recent advance in the provision of emergency contraception in the UK. It consists of two doses, each of one tablet containing 750 ug of levonorgestrel. The first dose is commenced within 72 h of intercourse and the second 12 h later. A recent randomized controlled trial involving over 4000 women showed that 1.5 mg of levonorgestrel taken as a single dose may be as effective as the usual regimen.

Efficacy Current evidence indicates that this is the more effective of the hormonal methods, with 86% of expected pregnancies prevented when started within 72 h of intercourse. As with the Schering PC4, the efficacy is higher the earlier it is started. Hepatic enzyme-inducing agents may reduce efficacy and an IUD should be considered. Efficacy may also be reduced if the patient vomits within 2 h of taking either dose.

It is improtant to remember that progestogen-only emergency contraceptives have some efficacy even beyond 72 h and up to 120 h. One estimate is 50-60%. It is a ‘better than nothing’ method for those women who present after 72 h, but are unable or unwilling to have an IUD fitted.

Prescribing Levonelle-2 The manufacturers advise that pregnancy, severe cardiovascular disease (arterial or venous), acute focal migraine and severe liver disease are contraindicated to the use of Levonelle-2.

Follow-up of patients It is usual to advise patients after use of emergency contraception to return in three weeks to exclude pregnancy. In practice, however, most patients do not return. It is therefore probably more important to ensure they are aware of what symptoms should lead them to seek medical advice should pregnancy occur. These include amenorrhea, an abnormal period, morning sickness, breast tenderness, urinary frequency, etc. After emergency contraception, the majority of women will have a normal period on time, but about 40% will have their period either prematurely or delayed.

Combined hormonal emergency contraceptives

Schering PC4 was licensed in 1994; its use has steadily risen since. However, after the introduction of progestogen-only emergency contraceptives its use has declined precipitously. Each tablet contains EE 50 Lig and norgestrel 500 Lig. The first dose of two tablets is commenced within 72 h of intercourse and the second two tablets are taken 12 h later.

Efficacy Current evidence indicates that this prevents between 57% and 74% of expected pregnancies when started within 72 h of intercourse. As with Levonelle-2, the shorter the coitus-to-treatment interval, the higher the efficacy. Hepatic enzyme-inducing agents may reduce efficacy and an IUD should be considered. In this situation, some advise an increase in the dose to two doses of three tablets each but the safety and efficacy of this have not been studied. Efficacy may also be reduced if the patient vomits within 2 h of taking either dose.

Hormonal emergency contraception will not provide ongoing contraception, and barrier methods should be advised for the rest of the cycle in which it is used. Future contraception should be discussed with the patient. Hormonal methods can be started with the next period.

Prescribing Schering PC4 The restrictions on use that apply to COCs do not apply to Schering PC4. In fact, the World Health Organization considers that — apart from pregnancy there are no contraindications to its use. In the UK, it is generally accepted that severe cardiovascular disease (arterial or venous), acute focal migraine and severe liver disease are contraindications to its use.

Follow-up of patients See Progestogen-only hormonal emergency contraceptives.

Intrauterine emergency contraception

When the earliest episode of unprotected intercourse was less than five days (120 h) previously, a copper-containing IUD can be inserted as an emergency contraceptive. When the earliest episode of unprotected intercourse occurred more than five days previously, a copper-containing IUD can be inserted up to five days after the earliest calculated day of ovulation, which is day 19 of a regular 28-day cycle. Unless ongoing contraception is required, the device is usually removed with the next period or when an alternative method of contraception has been established.

Efficacy This is the most effective method of emergency contraception: therefore, unless there is a contraindication it should be the woman’s decision to use it, not that of the doctor or nurse. The failure rate has been estimated to be 0. 1%.

Fitting emergency IUDs Assessment for an emergency IUD is very similar to assessing someone for an IUD for long-term contraception, with the exception that long-term effects such as menorrhagia are not relevant if it is to be removed with the next menstruation. Women requesting emergency contraception by definition have had unprotected inter-course and may be at risk of an STL Consideration should therefore be given to screening and prophylactic prescription of appropriate antibiotics. IUDs should be fitted by doctors or nurses with appropriate training.

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