Does the type of intrauterine device affect conspicuity on 2D and 3D ultrasound?

The objective of our study was to assess the conspicuity and position evaluation of intrauterine devices (IUDs) on 2D ultrasound and 3D ultrasound in nongravid patients.

Review of the ultrasound database for the period from July 2008 through June 2009 was performed for identification of patients with IUDs, of the type and position of the IUD, and of the patient's presenting symptoms. The conspicuity of the IUD on 2D sagittal and transverse planes and 3D coronal views was scored according to a 7-point scale. Data analysis was performed using the Student t test and the Pearson chi-square test.

Of the 269 patients with IUDs who had undergone ultrasound during the study period, 180 patients had a copper IUD; 59, a levonorgestrel-releasing device; and three, a Lippes loop. Twenty-seven IUDs were excluded because they were not seen on ultrasound (n = 15) or the type of IUD was not identifiable (n = 12). Of the 239 IUDs identified, the conspicuity score for copper IUDs (mean score, 5.3 [SD, 1.4]) differed significantly from that for levonorgestrel-releasing IUDs (mean, 3.1 [1.0]) on 2D ultrasound (p < 0.001). The difference in the conspicuity score for copper IUDs (mean, 6.6 [0.95]) versus that for levonorgestrel-releasing devices (mean, 6.2 [0.92]) on 3D ultrasound was marginally significant (p = 0.05). One hundred seventy-six IUDs (74%) were properly positioned within the endometrial cavity and 60 (25%) were malpositioned; proper positioning of three IUDs (1%) could not be confirmed. The indications for sonographic evaluation were pain (111/239, 46%), missing strings (91/239, 38%), and bleeding (34/239, 14%). Of the patients who presented with bleeding, the IUD was malpositioned in 13 (38%).

The levonorgestrel-releasing IUD is significantly less conspicuous than the copper IUD on 2D imaging. Three-dimensional ultrasound enhances the conspicuity of both types of IUD.