By Dr. Lisa Nakajima (biography, no disclosures)
What I did before
Intrauterine contraceptive device (IUD) use for contraception and management of heavy uterine bleeding is widespread, with approximately 14% of women aged 15-49 years of age using them worldwide1. It provides highly effective long-term birth control that is easily reversible. One of the risks of IUD insertion includes perforation of the uterus, which has an estimated incidence of 0.4-1.6 perforations per 1000 insertions. Risk factors for perforation include insertion performed by a less experienced clinician, patient lactation, less that 6 months post-partum, lower parity and a higher number of previous abortions1. Additionally, there is increased risk of uterine perforation with the use of a rigid sound or inserter, though I have always used a metal sound for this procedure, as this is how I was taught and what was demonstrated in medical school and residency.
What changed my practice
This past summer, working with a rural family physician who inserts many IUDs, I observed the use of a plastic endometrial aspirator as a uterine sound instead of a rigid metal sound. This was to decrease the risk of perforation. Looking at the literature, there have not been any randomised control trials on the use of sounds for insertion of IUDs. There are no studies looking at the rates of perforation between IUD insertions with or without sounds, let alone with metal versus plastic sounds, though it logically makes sense. There are investigators that question even the use of any sound and its actual benefit in an IUD insertion2.
One of the early IUDs includes a device called the Birnberg Bow, which had a rigid inserter, and a high uterine perforation rate of 1 in 2001. In the 1980s, in vitro studies showed that the force required to perforate a uterus with a metal sound was about 20 N and it would easily pass through the cornual, fundal, and lateral musculature3. Furthermore, the amount of force required to insert an IUD varied from 0.1 to 8 N. IUDs with flexible inserter tubes tended to bow if there was excessive cervical resistance and they were unable to perforate the uterus. These inserters would allow up to 10 N of force before bowing. There are no published studies on the newer and more commonly used devices, like the Mirena and Kyleena, looking at the amount of force required for their insertion.
What do I do now
Although uterine perforation is relatively uncommon and often does not cause long-term harm, it does increase the risk of unplanned pregnancy and often requires surgery to remove it. Consensus opinion states that perforation most commonly occurs at the time of insertion. In addition to perforation, metal sounds can also create false tracks. Therefore, I have chosen to use endometrial aspirators that are commonly used for endometrial biopsy sampling as a sound for IUD insertions, instead of the traditional metal sounds. The cost of an endometrial aspirator is about $4.95, which can be compared to the cost of sterilizing a metal sound in one’s clinic, and they are available in diameters that are similar to the IUDs themselves, often 3 or 4 mm. The Mirena IUD inserter has an outer diameter of 4.4 mm, while the smaller Kyleena IUD inserter is only 3.8 mm4&5. There is no data on the rates of endometrial perforation using an endometrial aspirator.
As mentioned previously, there is little literature on the actual benefit of sounding the uterus prior to this procedure. However, an IUD device can be quite costly financially to many patients, upwards of $400, and thus when practicing patient-centred medicine, this must be considered. When performing this procedure, I sound the uterus with an endometrial aspirator prior to opening the IUD. This way, if I am unable to pass the sound through the cervix, or if the uterus sounds to less than 6 cm, the device is not wasted. This allows me time to troubleshoot. At this point, I may consider re-attempting the procedure during menstruation, when the os is slightly wider. I may have her return after misoprostol 200 mg per vagina the night before. Or I may refer her to a more experienced physician.
References
- Rowlands S, Oloto E, Horwell DH. Intrauterine devices and risk of uterine perforation: current perspectives. Open Access J Contracept. 2016;7:19–32. DOI: 10.2147/OAJC.S85546. (View)
- Goldstuck ND. A minimalist technique for insertion of intrauterine devices. Healthc Low Resour Settings. 2015;3(1):5067. DOI: 10.4081/hls.2015.5067. (View)
- Goldstuck ND. Insertion forces with intrauterine devices: implications for uterine perforation. Eur J Obstet Gynecol Reprod Biol. 1987;25(4):315–323. DOI: 10.1016/0028-2243(87)90142-0. (Request with CPSBC or view with UBC)
- Bayer Healthcare Pharmaceuticals Inc. Mirena Full Prescribing Information. Revised June 2017. Accessed November 8, 2018. (View)
- Bayer Inc. Kyleena Product Monograph. Published 2018. Accessed November 8, 2018. (View)
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Is it possible to resterilize this sound? I am concerned about using plastics and single use items for the environment
“However, an IUD device can be quite costly financially to many patients, upwards of $400, and thus when practicing patient-centred medicine, this must be considered.”
I agree it’s important to only open the IUD once you are reasonably confident it can be inserted, however I have on occasion been able to sound with the pipelle only to then be unsuccessful passing the IUD insertion device through the cervix (I suspect because the inserter is wider than the pipelle). I keep in mind for these situations however – at least for the Mirena device – the company provides a replacement device free-of-charge if you open the package and are unable to insert the device due to contamination or other inability to insert the device. Similarly, if the IUD is expelled post-procedure, they will provide a replacement. In this way, it takes some of the pressure off of this being another cost for the patient if the procedure is unsuccessful despite our best efforts.
Where do you buy endometrial aspirators?
Many copper IUDs come with a single-use flexible plastic sound (example: The Liberté & Mona Lisa series). I save these if If they are not req’d: my practice has been to use the metal sound first, which our office sterilizes in a single IUD pack that has all the gear. If this is not successful, then I switch to the flexi-sounds. The use of the endometrial biopsy pipelle seems like a clever McGyver move, but they are a little pricey and cannot be re-resterilized.
I think it would be worth actually doing a study on this rather than just “assuming” it is better. Many things that have seemed like a good idea in the end have not proven to be any better.
I used to use endometrial samplers, but then found I could purchase a box of flexible plastic endometrial sounds for much less money. Saves my worry about perforation with metal sounds, nice easily visible cm markings. Down side, as mentioned above, is waste. Maybe a company will make a biodegradable version!
Another useful strategy for getting through a tricky internal cervical os are (reusable) os finders. These are malleable plastic rods of three different tapering diameters. Frequently, when the internal os seems elusive, using an os finder brings success. They can be curved to accommodate any angle between the cervix and the endometrial canal.
They will also facilitate gentle dilation up to the presenting diameter of the IUD inserter. It’s not so much the measurement of the endometrial canal depth, but getting through the os that determines the effectiveness of IUD insertion. Once the os has been navigated, and you know the exact path you will be following with the IUD, gently curving the loaded IUD insertion tube by using the IUD wrapper can help, as the angle between the cervix and the endometrial canal can be more acute in some women. (Mona Lisa and the Liberte silver-copper UT 380 IUDs have the most user friendly malleable insertion tubes.)
You can also use plastic sounds. Which are less expensive than endometrial pipelles and are used for their intended purpose.