The Hormonal IUD

A few of my readers and a not inconsiderable number of my patients have encouraged me to comment on the hormonal IUD (IntraUterine Device). In the UK, it is often known as the intrauterine system, but here in Canada it is best known as Mirena. It is a plastic T-shaped device containing a synthetic progesterone (levonorgestrel) inside a semipermeable membrane that allows a small and predictable amount of the hormone to diffuse through it and into the uterine cavity. The cavity, by the way, is also T-shaped -hence the shape of the device. Two thin monofilament nylon strings attach to the shaft of the T and protrude maybe a centimeter out of the cervix. If they are trimmed to an appropriate length, the man won’t notice them, but the woman can feel them to assure herself that the device is still in place. They are also how the IUD is removed.

The amount of progestin liberated is minute and shouldn’t have much effect on the rest of the body, but because progestins decrease the effect of estrogens on growth of the lining cells of the uterus, periods are often less heavy. Occasional spotting occurs in a small minority of wearers, but usually this disappears within a few months of its insertion. The device is good for five years and provides extremely good contraception that, unlike with oral contraceptives, is not affected by other medications that may be taken, and is not something that requires a daily smart-phone alert to remember.

In other words, it is by and large a well tolerated form of contraception, so I was surprised at the controversies swirling around it. True, the copper IUD has had its problem times. Quite a few years ago now, I think that too little thought was put into the selection of patients and IUDs were inserted into women with multiple sexual partners, or with a history of pelvic infections -both conditions which have since been shown to increase the risk of subsequent infections. Hopefully doctors are more careful about that nowadays… And anyway, those were copper IUDs which work by the copper ionizing and causing a (hopefully sterile) inflammatory reaction in the uterus. Sperm hate that, but germs often welcome the extra blood supply. Progestins, as I mentioned, don’t cause inflammation and in fact actually quieten uterine activity. So, apart from a very small risk of infection in the first month of use (perhaps from bacteria being introduced at the time of insertion) the device seems safe.

I also wondered if the controversy was related to the well-intended advice provided by the manufacturer about the risks. As one might hope and expect, pharmaceutical companies are supposed to disclose risks related to any of the components in their products. The Mirena contains a synthetic progesterone, so naturally other progesterone-containing products had their side effects listed. Depo Provera is one such medication and is well-known to have weight gain, spotting and even occasional irritability associated with it. Another product containing progestins are birth control pills. They sound even worse -especially when stripped of context: heart attacks, strokes, phlebitis -estrogen issues, mostly. But what a cursory reading of these problems misses, I suspect, is the minute dose of progestins that are being deposited only in the uterus without the need for huge amounts arriving from elsewhere that might really cause the unwanted effects.

In fact, I remember a patient that I had seen previously for contraceptive counselling who glared at me from the door, then sat down opposite me and pounded angrily on the desk. “I’m not going to let you shove a Mirena in me,” she said, as if she were going to leap over the desk and throttle me.

I tried to hide my startled reaction, all the while watching her other hand to make sure it wasn’t going for a weapon. “Why’s that?” I asked -somewhat timidly I have to admit.

The glare hardened. “Because it would be like wearing a bomb!” she screamed and walked out.

I put it down to too much media terrorist coverage at the time, but now I think I understand: we, as health professionals, should be helping our patients to navigate the labyrinthine halls of the internet complex. Not discouraging this, but helping them to read contextually instead. Carefully. Knowledgeably. Making them aware of the untrammelled pitfalls of naive searches; of Confirmation Biases that will limit their reading to what they want, or expect to find; and of agenda-driven blogs that may attempt to undermine any well performed research that hasn’t met with the writers’ experience.

The IUDs are not for everyone; they are merely members of a tool-kit of options, and as long as these are sensitively explored and adequately explained, they expand the choices in an admittedly personal and emotionally charged aspect of relationships nowadays. I’ve always hoped that the more choices there are, the more likely it is that one will actually be chosen. And used.

The use of the hormonal IUD is by no means confined to contraception either. I have to tell you that it has been one of the most useful tools I have at my disposal for patients with heavy, and otherwise uncontrollable menstrual bleeding. This can be especially troublesome in the years leading up to the menopause. It was, I suspect, why so many hysterectomies were being performed in that age group in years past. Progestins, remember, slow down the growth of cells in the uterine lining, so the less cells to shed with the period, the less heavy the period. Not a bad trade for hysterectomy. I make less money as a surgeon perhaps, but then again, I find that I sleep with less troubled dreams…

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