Mirena

The uterus may be too small to accommodate an intrauterine device (IUD) or the IUD may not open normally because of placement or anatomic abnormalities or it may become lodged in the lower uterine segment/cervix. The IUD may become embedded in the myometrium.

Three-dimensional ultrasound is crucial to determining the location of an IUD. Although the shaft of the IUD is visible using 2-D ultrasound, it is often more difficult to see the relationship between the arms of the IUD and the uterine cavity, especially if the IUD did not open normally or has become bent. Sometimes the shadow of the IUD is much easier to see than the IUD itself, especially when dealing with the non–copper–containing type. The shadow of the IUD often facilitates finding the IUD by following the shadow sonographically.

If an IUD is in the uterus, there is most often no other diagnosis to consider. If there is a shadowing structure in the uterus, however, other etiologies can include an area of calcification from a fibroid or endometrial scarring, or a foreign body such as a laminaria. If a patient has an ultrasound immediately after an endometrial biopsy or other instrumentation of the cavity, air left in the cavity can be very bright and echogenic with a shadow, simulating an IUD. Generally, the IUDs are a typical shape that is recognizable and not usually confused with these other conditions.

An abnormally located IUD can cause pelvic pain and bleeding, although this can also be an incidental finding in an asymptomatic patient. If a patient with an IUD presents with pain or bleeding, a 3-D ultrasound should be done to evaluate the position of the device in the uterus. Malpositioned IUDs need to be removed to improve symptoms.