More than half of the IUDs were malpositioned in a retrospective study of women who became pregnant while using intrauterine devices.
Though the displacement may have occurred over time, a UT Southwestern Medical Center researcher suggests that routine sonograms after IUD placement would in the least confirm proper initial positioning.
"Gynecologists typically do a pelvic and speculum exam after placing an IUD, but there's no sonogram involved," said Dr. Elysia Moschos, associate professor of obstetrics and gynecology and lead author of the study, available online and planned for the May issue of the American Journal of Obstetrics & Gynecology. "Based on the results of our study, we believe that sonographic evaluation of IUDs after insertion and for surveillance should be a topic of ongoing consideration."
In the retrospective study of 42 women with IUD placement and a positive pregnancy test, 36 had IUDs that were visualized through ultrasound and 2D imaging. Fifteen of these IUDs were normally positioned, and 21 were malpositioned.
Dr. Moschos said obstetricians and gynecologists should consider sonograms as part of the protocol after IUD insertion and possibly schedule them annually for those with IUDs, which can remain in the body for up to 10 years.
IUDs are a highly effective form of birth control, and pregnancy rates are extremely low. In the rare cases where women do become pregnant while using an IUD, transvaginal sonography during the first trimester can reduce complications by determining the pregnancy and IUD location, as well as whether the device can be retrieved.
Pregnancies complicated by an IUD's presence are at increased risk for first- and second-trimester miscarriage or preterm delivery if the device is left in place. While removing the IUD reduces these risks, the removal process itself carries a small risk of miscarriage.
In the study, 31 women had intrauterine pregnancies, three had ectopic pregnancies and eight had pregnancies of unknown location (biochemical proof of pregnancy but no sac in the uterus). Such cases, Dr. Moschos said, might indicate an early pregnancy that hasn't shown itself yet, an ectopic pregnancy or a miscarriage. Each of the eight pregnancies of unknown location in the study resulted in spontaneous abortion. The three ectopic pregnancies were treated successfully.
All of the patients had given birth before, with an average of two previous deliveries each. Their mean age was 26. The average length of time their IUD had been in place prior to pregnancy was just over two years. At the time the pregnancy was confirmed and IUD location verified, the mean gestational age was eight weeks.
Sonograms of the 31 women with intrauterine pregnancies showed that eight had IUDs within the endometrium; 17 had malpositioned devices; and six had IUDs which were not visible. Patient symptoms were not necessarily predictive of IUD malposition. Some women reported bleeding, pain and missing IUD strings, but 11 women had no indications.
Twenty women went on to have full-term deliveries, while six had failed pregnancies of 20 weeks or less. The outcomes for five of the 31 women were unavailable. Ten of the term pregnancies had successful IUD removals, and five others had no identifiable IUDs, later diagnosed as device expulsions.