) is not echogenic and may be more difficult to see on ultrasound imaging. Although the vertical stem of the LNG-IUD is not clearly visible, in a sagittal section of the uterus it creates an acoustic shadow of about 2 cm between the echogenic proximal and distal ends of the stem and is seen to extend from above the isthmus to the fundus (Figure 1). Both arms of the crossbars are slightly echogenic and usually visible in a transverse section (Figure 2). The strings hanging at the proximal end are echogenic and may be seen in the cervical canal. Ideally the LNG-IUD should be located high in the uterine cavity, with both arms opened out in the fundus. To determine the location of a LNG-IUD using two-dimensional (2D) ultrasound imaging, we start with a sagittal section followed by a transverse section to identify the landmarks described above. Three-dimensional (3D) ultrasound examination may help and involves the following steps. Starting from the sagittal section, a volume is acquired with the acquisition angle set at 120 • . After reducing the size of the volume box of the region of interest (ROI), the green line of the ROI box is set to cover the IUD. To obtain good visualization of the position of the stem, as well as of both the arms, the ROI of the acquired 3D volume should then be placed just under the level of the uterine cavity in order to render the IUD's shadow (Figures 3-5 and Figures S1-S3 online).The LNG-IUD is a T-shaped device with a polyethylene frame containing barium sulfate. On the 32-mm vertical stem, there is a reservoir containing a mixture of LNG and silicone covered by a silicone membrane. Both arms of the horizontal portion measure 32 mm in total. The LNG-IUD is a highly effective mode of contraception 1,2 and, because it induces hypomenorrhea or amenorrhea, it is also used to treat menorrhagia, dysmenorrhea and adenomyosis 3 -5 .If the LNG-IUD is not visible on ultrasound examination, it has either been expulsed or has perforated the