Emergency contraception is also known as post coital contraception and can prevent pregnancy after unprotected intercourse. It is not quite true to say 'the morning after the night before' as it can actually work up to 72 hours of unprotected sex.
There are two forms of emergency contraception - one is by way of hormonal contraceptive tablets and the other is by insertion of a copper coil or intrauterine device (IUD).
The emergency contraceptive pills are high dose oestrogen pills and are taken in two separate doses. The first dose must be taken within 72 hours of unprotected intercourse followed by the second dose 12 hours later. It is important to make sure that there were no previous bouts of unprotected intercourse prior to this 72-hour window. If this was the case the woman could already be pregnant and the pills would be contraindicated. The IUD can be inserted up to five days after unprotected intercourse in the hope of preventing pregnancy.
Use of emergency contraception
Millions of women around the world have used emergency contraceptives effectively. However, it must be stressed that this is an emergency form of contraception and does not replace the ever-popular effective methods of regular contraception.
Principle indications for emergency contraception
- Unprotected sex: where consensual sex occurred with no contraception; rape or sexual assault with risk of pregnancy; coitus interruptus.
- Potential barrier method failures.
- Potential pill failure when alternative methods have not been used or have failed, eg. antibiotics used with pill.
Mode of action of emergency contraception pills
These high dose hormones act by delaying or inhibiting ovulation and/or by altering the transport of sperm along the tubes. They may also alter the lining of the endometrium so preventing implantation.
This is the most common method of emergency contraception and is named after a Canadian professor, A. Yuzpe, who first discovered its efficacy back in 1974. Two doses of high dose hormones are taken, followed by the same dose exactly 12 hours later. In England the term PC4 is used for emergency contraception. However, this is not licensed for similar use in this country, so usually the doctor will either supply the pills directly from the surgery or will give instructions on how to take pills from a brand packet.
Contraindications to the Yuzpe regime
Obviously emergency contraceptive pills are not effective if the woman is already pregnant. It is thought that on the current available evidence that the amount of hormone used in the Yuzpe method is so small that it should not have a clinical impact on risk of use with similar contraindications for the combined oral contraception. This would include severe cardiovascular complications, acute focal migraine or severe liver disease. However, these and other conditions are included amongst the contraindications in any data associated with emergency contraception, so it is up to the doctor at the time of prescribing to assess these risk factors. Similarly there are no drug interactions with the Yuzpe method that would contraindicate its use.
Efficacy of Yuzpe method
It is thought that this combined oestrogen progestogen method prevents at least 74% of pregnancies when treatment is initiated within 72 hours. A 1998 WHO trial also found that this combination method was more effective when treatment was initiated within 24 hours of unprotected sex.
Side-effects of Yuzpe method
Some women experience nausea and even vomiting when taking this high dose hormone method. Some centres routinely prescribe medication to counteract the nausea and vomiting. Examples used are Domperidone (but this can cause unusual side effects, affecting posture). Some centres prescribe Cyclizine, and other centres prescribe Motilium.
It is important to stress when prescribing this method of contraception that it only prevents pregnancy from this bout of unprotected pregnancy. It does not protect against pregnancy for the remainder of the menstrual cycle. Women must use an effective method of contraception or avoid sex for the remainder of the cycle until they get their next period.
Timing of next period after Yuzpe method
Most women will start their next period within three days of the expected date. Some start early and some may be up to seven days late. If, however a woman does not have a period 10 days after the expected date she should return for a pregnancy test. It is also possible that there may be some spotting before a full period comes after taking this high dose emergency contraception.
Intrauterine emergency contraception
A copper IUD is inserted up to five days after unprotected intercourse. Again this must be fitted by a trained doctor. Awareness of post insertion pelvic infection must be considered. Some centres do testing for sexually transmitted disease before fitting an IUD. Obviously if positive, appropriate management must be followed.
Efficacy of IUD
This is in fact, higher than emergency contraceptive hormones with a failure rate of less than 0.1%.
These include pain and heavier bleeding. However, an IUD fitted post coitally can be removed at the beginning of the next period if a woman does not wish to continue with it as a form of contraception.
Again established pregnancy is a contraindication for fitting an IUD. If a copper IUD is being fitted sensitivity to copper would contraindicate its use. Again expert fitting is advised.
How an IUD works
The IUD alters tubal and uterine transport and affects the sperm and ovum so fertilisation does not occur. Post coital use of an IUD does involve the same mechanism in some cases, but is more likely to interfere with implantation.
Failed emergency contraception
Since both methods may fail, women should discuss with their doctors any signs of pregnancy after use of either method. Signs include a missed period, nausea, inexplicable fatigue, sore breasts, headaches and frequency of passing water. If pregnant, women should attend their doctors for advice. Emergency contraception does not prevent ectopic pregnancy, where the pregnancy develops outside of the womb and such a pregnancy should be seen by a doctor at the earliest possible signs. This includes pain on either side of the abdomen with spotting, especially after a light or missed menstrual period and associated dizziness.
Progestogen only emergency contraception
There is a progestogen-only form of emergency contraception which is not licensed in this country. The recommended dose is 75µg, which would necessitate taking a huge number of pills, in the order of 25 pills at one go. Again the method is to take the pills within 72 hours of unprotected sex and two doses are taken 12 hours apart. The efficacy of this regime is thought to be about 86%. Commonly associated side effects of this method include nausea and vomiting. Again it is contraindicated if pregnancy is established. There is thought to be no other contraindication.
Ongoing contraception and other follow-up
It is important that these visits for emergency contraception are used as a forum for discussing future contraception. Options should be discussed, and even prescribed - depending on the consultation. Obviously, precautions must be taken or intercourse avoided until the next period when the appropriate form of contraception is started.
Availability of emergency contraception
Your local GP in many cases will prescribe emergency contraception. Phone the doctor's secretary to check in advance. If not, most doctors who advertise in the Yellow Pages prescribe emergency contraception. Family planning clinics around the country also prescribe emergency contraception.
Written by Dr Claire McNicholas, general practitioner, Dublin
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