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Intrauterine device (IUD) failures are rare, but when pregnancies do occur it's usually because the device was not properly positioned or had disappeared completely, according to a new study.
"More than half of IUDs found in the first trimester of pregnancy were malpositioned. 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," co-author Dr Elysia Moschos said.
Over the course of a year, the gynaecologists at the University of Texas South-western Medical Centre in Dallas placed more than 4,100 IUDs. Dr Moschos and Dr Diane Twickler reviewed data on 42 women with positive serum human chorionic gonadotropin in the first trimester despite IUD placement.
As reported online in the American Journal of Obstetrics & Gynaecology, there were 31 intrauterine pregnancies and three ectopic pregnancies. Locations were unknown in eight.
The findings
Devices were correctly positioned in all three ectopic pregnancies. But 17 of the intrauterine pregnancies (55%) involved malpositioned IUDs, and in six (19%) the device had been expelled.
The three ectopic pregnancies were successfully treated, and the eight pregnancies of unknown location ended in spontaneous abortions.
Twenty intrauterine pregnancies ended in term deliveries. Another six failed at 20 weeks or less, and outcomes in the remainder were unknown.
Altogether, 75% of the patients presented with complaints - usually pain or bleeding. Three quarters of women complaining of pain had a malpositioned IUD, compared to less than half of those who complained of bleeding. Although the difference was not significant, the researchers suggest that such symptoms may be informative.
Sonographic evaluation of IUD placement is not currently the standard of care at their hospital, but the two authors say that "as a direct result of this study, we are now contemplating a protocol implementing sonographic imaging after placement of IUDs to confirm proper positioning."
(Reuters Health/ March 2011)
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