How to identify and localize IUDs on ultrasound

Although an ultrasound is not required after uncomplicated placement of an intrauterine device (IUD) or during routine management of women who are doing well with an IUD, it is invaluable in the evaluation of patients who present with pain or other symptoms suggestive of IUD malpositioning.

In this article, we outline the sonographic features of the IUDs available today in the United States and describe the basics of localization by ultrasound.

Related articles: STOP relying on 2D ultrasound for IUD localization. Steven R. Goldstein, MD, and Chrystie Fujimoto, MD (August 2014)
Update on Contraception. Melissa J. Chen, MD, MPH, and Mitchell D. Creinin, MD (August 2014)

Ultrasound features of IUDsWhen positioned normally, an IUD is centrally located within the endometrial cavity, with the crossbar positioned in the fundal area.¹ Copper and progestin-releasing IUDs can be identified easily on ultrasound if one is familiar with their basic sonographic features:

• Copper IUD: The central stem is uniformly echogenic due to its copper coils (FIGURE 1)
• Levonorgestrel-releasing intrauterine system (LNG-IUS): The LNG-IUS consists of a plastic sleeve that contains the progestin and surrounds a central stem. This configuration causes acoustic shadowing and has a characteristic “laminated” sonographic appearance with parallel lines (FIGURE 2). The Mirena IUD has echogenic arms due to barium sulfate, as well as an echogenic distal tip, with acoustic shadowing from the stem. Skyla is similar except for a highly echogenic silver ring on the stem approximately 3 to 4 mm inferior to the crossbar. On occasion, the echogenic strings of Mirena and Skyla can be mistaken for the device.

Three-dimensional ultrasound is useful in imaging of an IUD. If a patient’s IUD cannot be visualized by ultrasound, plain radiography of the kidney, ureter, and bladder may be helpful. If an IUD is not apparent on plain film, consider that it may have been expelled.

Potential malpositioningA malpositioned IUD may be partially expelled, rotated, embedded in the myometrium, or perforating the uterine serosa.

Related article: Malpositioned IUDs: When you should intervene (and when you should not). Kari Braaten, MD, MPH, and Alisa B. Goldberg, MD, MPH (August 2012)

In a retrospective case-control study that compared 182 women with sonographicallyidentified malpositioned IUDs with 182 women with properly positioned IUDs, Braaten and colleagues found that suspected adenomyosis was associated with malpositioning (odds ratio [OR], 3.04; 95% confidence interval [CI], 1.08–8.52), but a history of vaginal delivery was protective (OR, 0.53; 95% CI, 0.32–0.87).² A distorted uterine cavity also increases the risk of malpositioning.³

Although no uterine perforations were reported in a review of the LNG-IUS, expulsions were reported and may be more common among women who use the IUD for heavy menstrual bleeding.⁴

Additional images

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