IUD Issues: Zero in with ultrasound
Dr Shipp is a Vice President with Diagnostic Ultrasound Associates, PC, Brookline, Massachusetts, and a Sonologist and Associate Professor of Obstetrics, Gynecology and Reproductive Biology at Brigham & Women’s Hospital, Department of OB/GYN, Boston.
Dr Bromley is a Vice President at Diagnostic Ultrasound Associates, PC, Brookline, Massachusetts, and a Sonologist and Professor of Obstetrics, Gynecology and Reproductive Biology (part time) at Massachusetts General Hospital, Department of OB/GYN, Boston.
Neither author has a conflict of interest to report in respect to the content of this article.
Use of long-acting reversible contraceptives (LARCs) among premenopausal women has increased 5-fold during the past decade.1 The intrauterine device (IUD) is the most popular LARC, used by 6.4% of women aged 15–44 to prevent pregnancy.1 IUDs have also been proposed as a treatment for menorrhagia.2,3
The 2 most commonly available types of IUDs in the United States are nonhormonal copper-containing devices (copper T-380A; ParaGard, Duramed Pharmaceuticals), and hormone-releasing systems Mirena and Skyla (Bayer HealthCare Pharmaceuticals Inc.). Both have a T-shaped polyethylene frame compounded with barium sulfate to make them radiopaque, enhancing their appearance by radiography but not by ultrasound.
The ParaGard has a thin copper wire wrapped around the shaft and along a section of each of the straight arms, making it brightly echogenic by ultrasound (Figure 1 A,B,C). The Mirena and Skyla have slightly bowed arms and a central silicone reservoir around the stem that releases levonorgestrel (Figure 2,3).
The ParaGard and Mirena measure 32 mm across the arms and have a shaft length of 36 mm and 32 mm, respectively. The Skyla is slightly smaller with a transverse arm dimension of 28 mm and a length of 30 mm. In addition the Skyla has a sonographically visible small silver ring on the stem at the base of the arms. Monofilament retrieval strings are attached to the most inferior portion of the stem and can occasionally be sonographically recognized, depending on their location and other imaging characteristics such as the presence of cervical mucous (Figure 4).
IUDs are well tolerated by most women, with continuation rates of approximately 80%.2 Changes in menstrual bleeding may occur after placement of an IUD. Heavy bleeding and dysmenorrhea are more common with copper IUDs; amenorrhea is more common with progesterone-containing IUDs.3 Abnormal bleeding, pelvic pain, and inability to identify retrieval strings on physical exam may trigger a referral for imaging of the pelvis.4
Best technique for ultrasound evaluation
Sonography should be the first choice for imaging the female pelvis.5,6 It is readily available, much less expensive than other imaging methods, and does not place the patient at risk for radiation exposure. Multiple studies have demonstrated the utility of sonography in visualizing IUDs and characterizing their placement.4,7-11 Although most IUDs can be visualized with transabdominal ultrasonography, higher-frequency transvaginal ultrasound probes with resultant heightened resolution make transvaginal sonography optimal for evaluation of IUDs.