Emergency Contraception
Emergency Contraception |
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Key words: Emergency contraception , Levonelle, Intrauterine contraceptive device.
Introduction
Millions of unintended pregnancies occur world wide due to lack of or misuse
of contraception, contraceptive failure, or sexual assault. Emergency contraception
(EC) is the use of a drug or device as an emergency measure to prevent pregnancy
after unprotected sexual intercourse. This article reviews the mechanism of
action, side effect profile, the principal indications and contraindications
of EC, safety and efficacy of the various hormonal types of EC as well as the
use of the intrauterine device (IUD) for the same.
EC remains under utilised particularly due to lack of awareness among the clients.1-3 Barriers to access and low patient and provider awareness limit the use of EC in preventing unintended pregnancies. A recent study in London found that many young women did not take EC when they needed it because they encountered personal difficulties obtaining it or they misjudged their risk of getting pregnant.4 A survey was done recently to assess the level of awareness of EC among the clients attending community contraceptive advisory clinics in the Middlesbrough and Langbaurgh area. A brief summary of the findings of this survey is included in this article.
Methods of emergency contraception
Currently, there are several different interventions available for EC but at
the time of writing this article only two methods of EC are licensed in the
United Kingdom (UK). They are the progesterone only hormone method and the insertion
of an intrauterine copper-containing device (IUD).
Oestrogens
Oestrogen was first utilised as EC in the 1960s to prevent pregnancy in women
who were victims of sexual assault. The most widely used regimen was five 1-mg
tablets of ethinyl oestradiol given for five days. Reported failure rates were
between 0.6 and 1.4%. The main disadvantage of this regimen was the significant
side effects women experienced: nausea in 70 % and vomiting in 33%.5 Safety
concerns with this method appear to be minimal. While one small study suggested
a detrimental effect on clotting factors, a similar study failed to show any
consistent effect.6
Ethinyloestradiol and levonorgestrel
The first method of EC to be licensed in the UK (in 1984) was Schering PC4.
This was later withdrawn from the market in 2002. One pack of Schering PC4 consisted
of four tablets, each containing 50 mcg ethinyloestradiol (EE) and 250 mcg of
levonorgestrel (LNG). The regimen is often called the Yuzpe regimen after the
gynaecologist who first described the method.7 In 1999, a review of efficacy
studies estimated that the combined oestrogen-progesterone regimen prevents
at least 74 % of expected pregnancies when treatment is initiated within 72
hours.8 Unfortunately, side effects were relatively common with the Yuzpe method
in the form of nausea and vomiting. A study conducted by the World Health Organisation
(WHO) in 1998 reported that 50.5% of women who used the combined oestrogen-progestogen
regimen experienced nausea, and 18.8% reported vomiting.9
Levonorgestrel
The WHO sponsored studies done in Asia and Europe in 1998 comparing the Yuzpe
method to a progestogen-only regimen, levonorgestrel 0.75 mg given in two doses
12 hours apart within 72 hours of unprotected intercourse, revealed that the
progestogen-only regimen was more effective and was associated with less nausea
and vomiting (23.1% of women who used the progestogen-only regimen had experienced
nausea and 5.6% reported vomiting).9 The study demonstrated that the progestogen-only
regimen prevented 86% of expected pregnancies when treatment was initiated within
72 hours of unprotected sex. The study concluded that the progestogen-only regimen
is a very safe regimen with pregnancy being the only contraindication.
The Committee on Safety of Medicines approved the progestogen-only emergency
contraceptive pill formulation Levonelle-2 (Schering) for use in the UK in 1999.
One pack of Levonelle-2 consists of two tablets, each containing a 750-mcg dose
of levonorgestrel. The first dose (one tablet) must be taken within 72 hours
of unprotected intercourse (within 24 hours for best effect) and the second
dose is taken 12 hours after the first. It has recently been deregulated by
the UK government, at the manufacturer’s request, from a prescription-only
medicine (POM) to a pharmacy (P) status, thus allowing over-the-counter sales
in pharmacies to women needing EC.
Mifepristone
Mifepristone (RU 486) was the first progesterone antagonist to be developed
and it has been used for both medical termination of pregnancy as well as emergency
contraception. Glasier et al. compared 600 mg mifepristone to the Yuzpe method
and showed similar efficacy rates and fewer side effects; however 42% women
experienced delay in the onset of menstruation of more than 3 days.10 A recent
study from WHO demonstrated an efficacy greater than 85% for three doses of
mifepristone (600mg, 50mg, and 10 mg) with no significant difference between
them in terms of efficacy but less delay in the onset of next menstruation with
the 10 mg dose.11 Mifepristone has anti-glucocorticoid effects hence contraindications
to mifepristone include severe asthma, long term use of glucocorticoids and
adrenal insufficiency.12 Unfortunately the use of mifepristone as an abortifacient
jeopardises its development as an effective EC method.
Mechanism of action of hormonal EC
The exact mode of action of hormonal regimens is not known and probably varies
depending when they are used in the menstrual cycle. Inhibition or delay of
ovulation, alteration of the endometrium impairing fertilisation and implantation
are the three most probable mechanisms of the Yuzpe method. Several possible
mechanisms of action of levonorgestrel only method have been suggested. They
include thickening of the cervical mucus impairing sperm transport, alkalisation
of intrauterine pH causing rapid disappearance of living sperm and changes in
the endometrial lining impairing fertilisation and implantation.13
The possible mechanism of action of mifepristone is related to when it is taken
in the menstrual cycle. When administered in the pre-ovulatory phase mifepristone
halts follicular maturation in low doses. In higher doses, it blocks ovulation
and prolongs the follicular phase. When administered after ovulation, mifepristone
alters endometrial maturity and impairs implantation of the fertilised egg.
Intrauterine device
The copper IUD was introduced as a form of EC in the UK in 1976. It is a highly
effective form of EC with treatment failure rates at less than 1% and can be
inserted up to 5 days after the earliest estimated date of ovulation (i.e. up
to day 19 in a woman with a 28-day cycle). IUD insertion is an invasive procedure,
not always acceptable to women requesting postcoital contraception who are often
young and nulliparous. However it is particularly useful for women who wish
to continue with the method for long-term contraception. Contraindications to
IUD use include pregnancy, history of Wilson’s disease and active pelvic
infection. The mechanism of action of the IUD is thought to occur through its
effects on the endometrial lining. The IUD causes a sterile foreign body reaction
in the endometrial cavity that diminishes the viability of ova, the number of
sperm reaching the fallopian tube and their ability to fertilise the egg. The
IUD also possibly inhibits implantation of the fertilised egg. The effectiveness
in using levonorgestrel-releasing IUDs as EC has not been evaluated hence it
is not recommended for postcoital use.
Principal indications for emergency contraception
This is based on the recommendations for practice issued by the Faculty of Family
Planning and Reproductive Health Care in April 2000.14
1. Unprotected sexual intercourse
2. Potential barrier method failures, e.g. condom rupture, diaphragm/cap inserted
incorrectly, torn, dislodged during intercourse, removed within 6 hours of intercourse.
3. Potential pill failure when alternative methods not used/failed
3a.Combined pill:
Efficacy of regular (non-emergency) combined pill compromised, e.g. unprotected
sex/failure of barrier method within seven days after:
• two or more pills missed from the first seven pills in a packet, or
• four or more pills missed mid-packet
If two or more combined pills are missed from the last seven pills in a packet, emergency contraception is not necessary provided that the pill-free break is omitted i.e. the woman starts her next packet of pills the day after finishing the current packet.
3b. Progesterone only pill:
Efficacy of regular (non-emergency) progesterone only pill compromised, e.g.
unprotected sex/failure of barrier method within seven days after:
• one or more pills taken more than three hours after usual pill-taking time, or missed
4. Potential IUD failure. Complete or partial expulsion of an IUD; mid-cycle IUD removal considered absolutely necessary
5. Risk of conception while advised to avoid pregnancy, e.g. following administration of cytotoxic drugs or potentially teratogenic agents.
Where there is anxiety, consider treating rather than waiting to see what happens. This is because there is no day since the last menstrual period (LMP) when a clinician can be certain that unprotected sex would not result in pregnancy. More so if the woman reports having irregular periods or is unsure of her dates.
Emergency Contraception Awareness Survey
An anonymous confidential questionnaire survey was done in the South Tees area
over a period of three months in 2001 to explore the level of knowledge of awareness
of emergency contraception (EC) among clients attending contraception advisory
clinics. 380 consecutive clients who attended three chosen clinics volunteered
to participate in the survey. The main outcome measures were to assess
• Knowledge of the existence of emergency contraception
• Awareness of the two main methods of emergency contraception
• Knowledge of the correct time limits for hormonal EC and for the use
of the intrauterine device as EC
Findings of survey
• 370 (98%) clients had heard about EC.
• The age range of the clients was 14-56 years (mean 25 years).
• Although 356(94.2%) clients were aware of the hormonal method of EC,
only 217(57 %) were aware of the correct time limits (up to 72 hours).
• Awareness of intrauterine contraceptive device (IUD) as a method of
EC was generally low (36 %) and only 13% knew that it was effective for 5 days
after unprotected sexual intercourse.
Conclusion
Though the survey demonstrated a high general awareness of hormonal method of
EC, the knowledge of IUD as a method of EC was poor. The clients were unaware
of the specific details regarding the effective time limits of both methods
of EC. It clearly demonstrates that there is a need for more publicity to improve
awareness of both methods of EC. Health education initiatives should concentrate
on improving the knowledge of specific details of efficacy, safety and side
effects of EC among the general population. Safe and effective options for emergency
contraception are available to women, however the awareness is generally low.
Future research would involve finding an optimal dose of mifepristone and using
single-dose levonorgestrel (15)
References
©2001 Sexual Health Matters. Published Quarterly by Express Print Works, Middlesbrough,
UK
ISSN 1469-7556
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