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What’s an IUD?

What’s an IUD?

Doctor and Patient

IUDs are Intra-Uterine Devices. They are small, usually T shaped devices which are placed into the uterus to address a number of women’s health issues. The most common of these is to prevent pregnancy, so acting as contraceptives. However, some IUD’s can also help to manage menstrual flow and also protect the lining of the womb when using hormonal treatment in the menopause.

There are two main categories of IUD

  • Hormonal: these devices contain a small amount of progesterone hormone and work as contraceptives in many ways while also reducing the amount of menstrual blood loss, and may remain in the uterus for up to 5 years. Hormonal IUDs available in Australia are Mirena, and Kyleena
  • Non-hormonal: these devices are made of copper, are only used as contraceptive devices, and may remain in the uterus for up to 5 or 10 years depending on the device chosen. Copper IUDs available in Australia are TT380 (short or standard) and Multiload

How does it work?

Copper IUD Hormonal IUD
Contraceptive Actions
  • The “arms” of the device block the entrance of the fallopian tubes preventing the egg from entering the uterus.
  • The device DOES NOT stop ovulation.
  • The copper metal in the device is spermicidal, so it kills some of the sperm.
  • The copper in the device causes a reaction on the lining of the womb (endometrium) which prevents implantation of a fertilized egg.
  • The “arms” of the device block the entrance of the fallopian tubes preventing the egg from entering the uterus.
  • The device DOES NOT stop ovulation.
  • The progesterone hormone in the device thickens mucous in the cervix, making it difficult for the sperm to swim through the cervix into the uterus
  • The progesterone hormone in the device thin the lining of the womb (endometrium) which prevents implantation of a fertilized egg
Other Actions
  • The thinning of the endometrium which occurs because of its exposure to progesterone in the device, means that periods are lighter and in some cases absent
  • This thinning is also protective to the effects of estrogen therapy used in the menopause

The hormonal IUD’s differ in the level of their hormone content (Mirena contains slightly over twice as much progesterone than Kyleena) and this dictates the circumstances in which they may be used:

Mirena Kyleena Copper IUD
Circumstances for use
  • Contraception
  • Heavy menstrual bleeding
  • Endometriosis
  • Endometrial protection with estrogen replacement in the menopause
  • Contraception
  • Slightly reduce menstrual blood loss
  • Contraception
  • Emergency contraception up to 5 days post unprotected intercourse
Young woman holding a copper IUD in her hand

Both hormonal IUD’s provide improvement in menstrual blood flow because of the effect of the progesterone on the endometrium, however, the copper device may result in heavier more painful periods because of the reaction that copper exposure causes to the endometrium. With the Mirena device, owing to its greater progesterone content, up to 70% of women will not have periods despite continuing to ovulate, and the remaining will experience up to a 95% reduction in menstrual blood flow, all as a result of the thinning of the endometrium which occurs because of progesterone exposure. Because of the lower progesterone content of the Kyleena device, while there is generally some reduction in menstrual blood loss, it is not as significant as that with Mirena, and is unlikely to lead to cessation of periods.

While the hormonal IUDs contain progesterone, the majority of this hormone is released locally in the uterus. Less than 2% of the progesterone content of the IUDs is absorbed into the blood circulating the body. This equates to taking one contraceptive pill a week with the Kyleena and slightly more with the Mirena. This means that the blood content of hormone associated with using the hormonal IUDs is much less than that associated with taking any other hormonal contraception, and because of this, side effects are much less common.

All IUDs provide extremely reversible contraceptive effects, so once they are removed, pre insertion fertility and menstrual cycle is restored within 2-4 weeks.

How is it fitted?

Fitting of both types of IUD can only be carried out when we can confirm that there is no pregnancy or risk of pregnancy, except for circumstances in which the copper IUD is used as emergency contraception within 5 days of an episode of unprotected intercourse. For this reason, it’s best to fit the device during the first 7 days of the cycle (during the menstrual period) ideally after the heaviest days of menstrual blood loss have passed, but while there is still some menstrual flow. Fitting at this time is also beneficial, because the cervix is softer, easier to stretch, and slightly open making fitting the device less uncomfortable.

During the fitting, the doctor usually performs a vaginal examination to determine the angle in which the uterus is positioned. Then, a speculum device is inserted into the vagina to visualize the cervix – this is the same device used during cervical screening. Once visualized, the cervix and vagina are cleaned using antiseptic solution. Then the uterus is then anchored using an instrument which is attached to the cervix. Then the size of the uterus cavity is measured using a long thin measuring device which is passed through the cervix to the top of the uterus. This allows us to assess how far into the uterus we must insert the IUD. The IUD is inserted via a long thin insertion tube inside which the device and its arms are folded. When the appropriate length has been reached, the IUD is released from the insertion tube, and the insertion tube is then carefully removed. The threads of the IUD sit outside of the cervix (but not outside the vagina) and these are trimmed to between 2-3cm in length. The cervix and vagina are cleaned again, and the speculum is removed.

The insertion procedure does cause some discomfort particularly as the IUD is released from the insertion tube. This results from the muscle of the uterus cramping in response to the presence of a foreign body inside the uterus cavity. The cramping is similar to cramping pain related to periods, but can feel a little sharper. However, it usually is worst during the few minutes associated with releasing the IUD into the uterus (usually 5 minutes at most), and then reduces quite quickly. There are options for pain management during this time, but it’s important to note that most of the pain comes from the cramping of the uterus which cannot be managed with pain control used in the vagina or cervix. Evidence tells us that breathing techniques and guidance and explanation by the fitter during the procedure are as effective as local anaesthetic or pain controlling agents. Sedation is used by some practitioners for this short procedure, but there are risks associated with sedation which must be weighed carefully against the duration nature and severity of the pain experienced. It’s normal for the cramping to continue less severely for the first few hours after insertion and it generally settles down in the 2 days following insertion. Simple pain control is sufficient to manage this, and heat packs can also help.

Post insertion care is important particularly for the first 3 days following insertion, when the risk of infection is higher. The copper IUD is effective as a contraceptive immediately post insertion, while the hormone IUDs take 7 days to become effective while the effect of the progesterone kicks in. During this time extra contraceptive precautions must be used.

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