The MirenaTM coil – an intrauterine system (IUS) – is familiar to many women as a long-term contraceptive. However, it can also be beneficial to some perimenopausal women for use as the progesterone component of hormone replacement therapy (HRT). Progesterone must be taken by women who have a uterus if they are using estrogen HRT because the build-up of the womb lining needs to be kept in check, or else the risk of uterine cancer is raised.
What is the Mirena coil?
The MirenaTM coil is a small, plastic, flexible, T-shaped instrument with a stem and ‘arms.’ It is fitted inside the uterus. Once done, it slowly and continuously dispenses levonorgestrel, a synthetic form of progesterone, directly into the uterus.
The benefits of the MirenaTM coil for perimenopausal women on HRT
For some women, the MirenaTM is a beneficial and safe method of taking the progesterone component of HRT. It can minimize the Premenstrual Syndrome (PMS)-type symptoms that sometimes become more troublesome during perimenopause. This is especially relevant for those with a progesterone intolerance, for whom taking tablets can significantly worsen PMS-type symptoms, and even more so for those susceptible to Premenstrual Dysphoric Disorder (PMDD). The progestin (synthetic progesterone) is released by the MirenaTM in a slow, continuous, and low dose, going directly into the uterus and delivering only a low systemic dose into the bloodstream. Suppose PMS and PMDD sufferers notice their symptoms worsening on the Mirena. In that case, it may be due to the synthetic nature of the progesterone (despite its low systemic dose); in this case, they might find bio-identical forms (like Utrogestan) better.
The MirenaTM tends to lighten or stop periods in most women, reducing flow by up to 90%, which is a benefit to those suffering from heavy perimenopausal bleeding. It can also reduce menstrual aches and pains. It has the added benefit of providing birth control at a time when pregnancy is still possible. Because the MirenaTM is fitted every 4-5 years, remembering to take a pill is not an issue.
How the Mirena coil is fitted?
A healthcare professional fits the MirenaTM coil. They may want to perform a pelvic examination to determine the size and position of the uterus, an ultrasound for those over 40, a pregnancy test, and screen for sexually transmitted diseases before fitting the MirenaTM. These are to avoid any complications.
While fitting the MirenaTM is quick (5-10 minutes), it can be uncomfortable, with some women reporting cramping and dizziness. If you suspect this may apply to you, discuss it with your doctor beforehand. They may prescribe a local anesthetic. It is important to say if there is discomfort during the procedure. If it is too uncomfortable, you can ask for it to stop.
The vagina is held open by inserting a speculum. The cervix is cleaned, and at this point, a local anesthetic may be given. An applicator tube containing the Mirena will be inserted, and when the applicator is withdrawn, the coil stays in place. Two strings attached to the coil pass through the cervix into the vagina, and these may be trimmed so they don’t protrude too far. The strings are there for the eventual easy removal of the MirenaTM. They should not be noticeable during sex.
On rare occasions, inserting the device can be difficult, and your doctor will discuss alternatives instead.
Your doctor may examine you a month after fitting to ensure the coil is still in place and there are no signs of infection.
Removing the Mirena coil
The MirenaTM coil is removed by pulling on the strings that protrude into the vagina. This should only be done by a healthcare professional. It can be withdrawn at any time, including if you experience adverse effects or change your mind, in addition to when it is time for a replacement.
Mirena coil safety and side effects
While there are minimal risks during MirenaTM coil insertion, there is a small risk (around 1:800,000) of perforating the uterus, which would require surgery. There is also a small risk of pelvic infection in the first weeks after fitting the device.
You may bleed for a few days after the MirenaTM is fitted or experience menstrual-type cramps. In the first few months post-insertion, spotting or irregular bleeding commonly occurs. Likewise, during this time, some common side-effects may occur. These include breast tenderness, bloating, mood swings, fluid retention, acne, and headaches. These should all settle after the first few months. If they do not, or if they become particularly troublesome – as can happen for those women with a severe progesterone intolerance – the MirenaTM may need to be removed.
It is important to check periodically (every month or so) that the MirenaTM’s strings are still protruding into the vagina. You can do this using your fingers. Do not pull the strings, as this may dislodge the coil. If you cannot feel the strings, or if you can, but they are protruding further into the vagina, or if you think the MirenaTM has become dislodged, you must inform your doctor immediately.
In up to 5% of women, the MirenaTM may be expelled or dislodged. If this happens, you should see your doctor. The MirenaTM can cause abdominal pain and bleeding in some women. If this occurs, seek medical help immediately. Likewise, see your doctor immediately if you come into contact with an STI, develop unusually heavy and persistent bleeding, experience abdominal pain, have pain during intercourse, develop an unexplained fever, or have an abnormal or foul-smelling discharge.
While the MirenaTM is an effective contraception, in rare cases, pregnancy can occur. If you suspect you are pregnant, see your doctor immediately, as this can be fatal or result in infertility and miscarriage.
Who shouldn’t use the MirenaTM coil?
The MirenaTM coil is unsuitable if you get infections easily or have certain cancers. It is not suitable as HRT for those who have suffered a stroke, heart attack, or heart problems. Your doctor should take into account your health records when deciding if the MirenaTM coil is suitable for you.
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