Abnormal uterine artery Doppler flow predicts early stillbirth
NEW YORK (Reuters Health) - An abnormal uterine artery Doppler flow is a good predictor of antepartum stillbirth at up to 32 weeks gestation, but not for stillbirth at term, British investigators report
In a study published in the January issue of Obstetrics and Gynecology, Dr. Gordon C. S. Smith at Cambridge University and colleagues analyzed uterine artery Doppler findings in 30,519 unselected women. Doppler velocimetry was performed between 22 and 24 weeks gestation.
There were 109 stillbirths, which the investigators classified as unexplained or placental -- including abruptio, pre-eclampsia, and growth restriction.
The median gestational age of a placental stillbirth was 30 weeks compared with 38 weeks for unexplained stillbirth.
There was a 5.5-fold increased risk of placental stillbirth among women with a mean pulsatility index in the top decile. Women with a bilateral uterine notch on Doppler had a 3.9-fold higher risk of placental stillbirth.
A mean pulsatility index in the top decile had a 2.5-fold increased risk of unexplained stillbirth. There was no association between a finding of a bilateral notch and unexplained stillbirth.
A combination of a high mean pulsatility index and bilateral notching had a sensitivity and specificity of 58% and 95%, respectively, and a positive likelihood ratio of 12.1 for predicting stillbirth of any cause up to 32 weeks gestation. The combination was a poor predictor of stillbirth after 32 weeks gestation.
"The data from the present study are essential for the design of any interventional studies that aim to reduce the risk of stillbirth in an unselected population screened using uterine artery Doppler," the researchers write.
Determining when risk of stillbirth increases with an increased resistance of uterine artery flow needs to be determined first, Smith and associates say. "The timing of the risk is essential for planning the timing of any intervention."
Obstet Gynecol 2007;109:144-151.