Intrauterine device

Seven copper-containing intrauterine devices (IUD) are currently available in the UK. Six have a plastic frame with copper wire wound round the stem or copper sleeves on the end of the arms. The amount of copper varies from 250 to 375 mm2. One IUD is frameless (GyneFix®) and consists of six copper beads on a nylon thread. A knot at the top end of the thread is inserted into the fundal myometrium, the top and bottom copper beads are crimped to hold the string of beads in place. In all devices a tail protrudes through the cervical canal into the upper part of the vagina allowing easy removal. IUDs containing at least 300 mm2 of copper have the lowest failure rates. Devices containing 250 mm2 are licensed for 3 years, the T-Safe Cu 380A

for 8 years and the remainder for 5 years. The FFPRHC advises that an IUD inserted at or after the age of 40 can be retained until contraception is no longer required (i.e. beyond the licensed duration) [25]. There are good data to demonstrate efficacy up to 10 years for some devices and since the risks of perforation, infection and expulsion are all highest around the time of IUD insertion it makes sense to discuss prolonged continuation with the user.

Efficacy

In a WHO sponsored study of an IUD containing 380 mm2 copper, the failure rate was 1 per 100 women in the first year of use. Over 5 years of use, cumulative pregnancy rates for devices containing at least 300 mm2 are around 2%.

Mechanism of action

IUDs stimulate a marked inflammatory reaction in the uterus. The concentration of macrophages and leucocytes, prostaglandins and various enzymes in both uterine and tubal fluid increase significantly. It is thought that these effects are toxic to both sperm and egg and interfere with sperm transport. If a healthy fertilized egg reaches the uterine cavity implantation is inhibited.

Contraindications

There are very few women for whom a copper IUD is con-traindicated. A history of malignant trophoblastic disease, endometrial cancer or pelvic TB and current STI or PID (pelvic inflammatory disease) are the only WHOMEC category 4 conditions. Women at risk of STI and women with HIV or AIDS can use a copper IUD but should be carefully counselled about safe sex and additional condom use should be promoted. Unexplained vaginal bleeding should be investigated before IUD insertion and a distorted uterine cavity (due for example to fibroids) may make insertion impossible.

Side effects

MENSTRUAL DISTURBANCE

The effect of the IUD - particularly the effect on local prostaglandins - on the endometrium tends to cause increased menstrual bleeding and dysmenorrhoea. Bleeding can be both heavier and more prolonged particularly during the first 3 to 6 months of use. In clinical trials up to 15% of women will discontinue for these reasons. Removal rates for bleeding and pain are similar when the frameless Gynefix® is compared with a framed device containing 380 mm2 copper.

DYSMENORRHOEA

The presence of an IUD in the uterus is associated with an increased incidence of dysmenorrhoea. There is no good evidence that dysmenorrhoea is less among women using the frameless device.

ECTOPIC PREGNANCY

A meta-analysis of case control studies demonstrated no increase in the risk of ectopic pregnancy among current users, but the risk was increased among past users (OR 1.4; 95% CI 1.23-1.59) [26]. The absolute risk of any pregnancy is very low among IUD users and the annual ectopic pregnancy rate is 0.02 per 100 women years compared with 0.3-0.5 for women not using contraception.

PELVIC INFECTION

The risk of pelvic infection associated with IUD use has been overestimated. A meta-analysis suggested that the risk had halved during the 1980s [27]. Infection is most likely to occur during the first 20 days following insertion. Thereafter the risk of developing infection is not significantly higher than that among women using no contraception (<1.5 per 1000 women years). The risk can be reduced by using aseptic techniques during insertion and by restricting the method to women who do not have multiple partners and whose partners do not have multiple partners. Marital status and parity are really irrelevant to the risk of PID. Screening for STI is recommended prior to insertion in areas where the prevalence of infection is high and among individual women with known risk behaviours (including women under 25). Pelvic actinomyscosis can rarely occur in association with IUD use. Actinomyscosis-likeorganisms (ALOs) aresome-times seen on smears but if the patient is symptom free the IUD can be left and the smear repeated 6-12 months later. If there are symptoms the IUD should be removed avoiding contamination from the vagina and, after cutting off the tails which will be contaminated, sent for culture.

Insertion and removal

An IUD can be inserted at any time in the cycle if it can be reasonably certain the woman is not pregnant. Otherwise insertion should be limited to the first 7 days of the cycle. Post-partum insertion should be delayed until 4 weeks after childbirth for all women including breastfeeding women. An IUD can be inserted immediately after spontaneous or therapeutic abortion although expulsion rates may be higher in second trimester abortions. Unless pregnancy is desired, removal should only be undertaken in the late luteal phase or in the first 7 days of the cycle. In menopausal women the IUD should be left in for one year after the last menstrual period. If the IUD threads are not visible or snap during removal it may be possible to remove the device with a specially designed hook or a pair of artery forceps.

PERFORATION

Perforation of the uterus may occur at the time of insertion although it is often unnoticed. In large clinical trials it occurs in 1.3 of every 1000 insertions. Routine follow-up 6 weeks after insertion allows perforations to be detected. Absent threads should be investigated by ultrasound. At this stage the IUD can often be retrieved laparoscopically; left for months, local adhesion formation often necessitates laparotomy. The length of the uterine cavity should be measured using a sound and a tenaculum should be used at insertion to reduce the risk of perforation.

EXPULSION

The risk of expulsion is around 1 in 20. It is most common in the first 3 months of use and usually occurs during menstruation. Many clinicians advise that IUD users should regularly check to feel the IUD strings to detect expulsion. In reality this is often not easy to do and probably results in more anxiety than it prevents unrecognized expulsion.

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