IUD Issues: Zero in with ultrasound
Given biologic variability, minor manipulation may be necessary to rotate all planes to obtain a coronal view of the uterus and check the position of the IUD. The same standard orientation is recommended for both anteverted and retroverted uteruses. Therefore the initial manipulation of the volume of a retroverted uterus should be approximately 180° so that the anterior wall of the uterus is at the top of the image, making it appear to be anteverted (Figure 7 A and B).
With this simple technique the coronal plane of the uterus can be obtained in almost all women after acquiring the volume during transvaginal sonography. If the IUD is in the expected location within the uterus, it should be easy to identify in the coronal plane. If the IUD is not in its expected location, further manipulation may be necessary to characterize its position and to ascertain its location. On occasion, an IUD is not in its expected location, and the “T-shaped” view of the device is not in the same plane as the coronal view of the endometrium and, therefore, they cannot be displayed in one image. In some cases, visualization of the acoustic shadow of the IUD may help in determining its location13 (Figure 8).
Moschos and Twickler demonstrated that the copper T is more easily identified sonographically than the levonorgestrel-containing IUDs. These authors also showed that 3D sonography enhanced the “conspicuity” of both types of IUDs over conventional 2D ultrasound evaluation.8 Chen et al. evaluated malpositioned IUDs using the gold standard of hysteroscopy, laparoscopy, or laparotomy and found that 2D imaging correctly identified 65% of malpositioned IUDs whereas 3D ultrasound correctly identified 84% of malpositioned IUDs.9
Nowitzki et al. provided definitions for different types of abnormal or malpositioned IUDs.10
Expulsion: passage of the IUD either partially or completely through the external cervical os. The IUD is not seen on pelvic sonography.
Displacement: rotation or inferior positioning of the IUD in the lower uterine segment or cervix (Figure 8).
Embedment: penetration of the IUD into the myometrium without extension through the serosa.
Perforation: partial or complete penetration of the IUD through the serosa (Figure 9).
Fragmentation: retention of a broken piece of the IUD after expulsion or removal. Fragmentation of a retained IUD has been occasionally seen in vivo as well.14