An intrauterine device (intra meaning within, and uterine meaning of the uterus) is a birth control device also known as an IUD or a coil (this colloquialism is based on the coil-shaped design of early IUDs). It is a device placed in the uterus and is the world's most widely used and inexpensive method of reversible birth control. The device has to be fitted inside or removed from the uterus by a doctor or qualified medical practitioner. It remains in place the entire time contraception is desired. Depending on the type, IUDs can usually remain effective for 2, 5 or 10 years.
Types of IUDs
There are many types of IUDs worldwide, but only two types currently available in the United States: the copper-T intrauterine device (IUD) and the levonorgestrel-releasing intrauterine system (LNG IUS).
The copper-T IUD is marketed as ParaGard T 380A by Barr Laboratories. It was approved by the Food and Drug Administration (FDA) in 1984 and became available for use in 1988. The device consists of a T-shaped polyethylene frame that is wound with copper wire around the vertical stem and has copper bands on the lateral arms. The ParaGard T 380A is approved for up to 10 years of use, although limited data support its effectiveness for at least 12 years.
 Photo of copper-T IUD
The LNG IUS, marketed by Berlex Laboratories as Mirena, consists of a T-shaped polyethylene frame with a reservoir around the vertical stem that contains levonorgestrel. It was approved for use by the FDA in 2000. Initially the LNG IUS releases levonorgestrel at a rate of 20 µg per day. This rate decreases to approximately half that rate by five years. It is indicated for up to five years of use, although limited data support its effectiveness for at least seven years.
Effectiveness
The hormonal IUD is as effective as the contraceptive pill at preventing pregnancy; and the copper IUDs effectiveness ranges from 98% to over 99% depending on the brand. IUDs can not protect from STDs, and if an infection is caught while using an IUD it may be more likely to spread to the uterus.
Side-effects
Copper IUDs may make menstrual periods heavier or more painful in some women, especially for the first few months after they are inserted, but modern types such as the GyneFix have been designed so that they usually do not affect periods (compare with IUS).
IUDs have remained unpopular in the USA since the Dalkon Shield IUD (which had a multi-filiment string) was banned after being linked to several deaths (it was thought the thick woven string hosted bacteria, which could spread to cause reproductive tract infections and occasionally fatalities). IUDs with monofiliment strings (including all modern IUDs) are much safer and complications are very rare. The number of deaths attributed to the Dalkon Shield were more likely due to lax sterilization procedures conducted on the IUD.
It is commonly believed IUDs cause a greater risk of an ectopic pregnancy. However, recent studies have shown that women with IUDs actually have fewer ectopic pregnancies than women using no contraception. However, in the rare cases that a pregnancy occurs with an IUD in place that is not removed, it is more likely to be ectopic.
IUDs are not recommended for women who are suffering from a pelvic inflammatory disease.
Use as emergency contraception
Intrauterine devices can be used as emergency contraception to prevent pregnancy up to 5 days after unprotected sexual intercourse, or sexual intercourse during which the primary contraception is believed to have failed (e.g. a condom was used, but it broke). Insertion of a copper-T IUD as emergency contraception is more than 99% effective, making it more effective than Emergency contraceptive pills (ECP or 'morning-after pill').
IUDs may also be used where ECPs are less appropriate:
- ECP are contraindicated in those with severe liver disease or the very rare condition of porphyria
- ECP are currently licensed for only 3 days (72 hours) after coitus
- ECP will be ineffective if currently suffering from diarrhea or vomiting
- The effectiveness of ECP may be reduced by the herbal preparation St John's wort and enzyme-inducing drugs (e.g. antiepileptics or rifampicin)
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