The shadow of the intrauterine device.

OBJECTIVE

An intrauterine device (IUD) is a highly effective and prevalent form of birth control with a low failure rate. It is not without complications, including irregular bleeding and pelvic pain, perforation, expulsion, and pregnancy. Investigation of the symptomatic patient and routine follow-up of asymptomatic women with IUDs include transvaginal ultrasonography to rule out IUD malposition and other complications. Three-dimensional ultrasonography (3DUS) has been shown to have added value in imaging the pelvic organs, including the uterus. However, even with 3DUS, the operator may encounter difficulty in imaging the IUD in its entirety, because of variability in both echogenicity and exact location.

METHODS

More than 30 women undergoing IUD placement evaluation, including routine examinations and cases of suspected pregnancy, irregular bleeding, infection, and pelvic pain, were evaluated with 3DUS and volume contrast imaging in the C plane (VCI-C), which visualized acoustic shadows of the IUDs, facilitating identification of the intrauterine position and type of the device.

RESULTS

Four examples are presented from women undergoing evaluation of IUD placement in whom 2-dimensional ultrasonography failed to visualize the device satisfactorily. Volume contrast imaging in the C plane allowed visualization of the acoustic shadows of the IUDs, thereby providing more exact imaging of the type of device as well as aiding in locating the IUD. In a woman with irregular bleeding, a bicornuate uterus with pregnancy in 1 horn and a bowed T-type IUD in the contralateral horn were diagnosed with VCI-C.

CONCLUSIONS

We conclude from these shadow images that VCI-C is a useful modality in cases of difficult visualization of the IUD; VCI-C visualization of the acoustic shadow of the IUD may provide an adjunctive approach.