Uterine artery Doppler velocimetry in the detection of adverse obstetric outcomes in women with unexplained elevated maternal serum alpha-fetoprotein levels.

OBJECTIVE

We hypothesized that in pregnancies complicated by unexplained elevations of maternal serum alpha-fetoprotein, second-trimester uterine artery Doppler findings would detect adverse obstetric outcomes.

STUDY DESIGN

One hundred three subjects with unexplained elevations of maternal serum alpha-fetoprotein had uterine artery Doppler velocimetry studies performed at the time of targeted ultrasonographic examination (17 to 22 weeks). A resistance index > 95th percentile or the presence of a uterine notch was considered abnormal. Adverse outcomes included preeclampsia, preterm birth, low birth weight, intrauterine growth restriction, abruptio placentae, and fetal death. Statistical analysis was performed by Student t test, chi 2 analysis, and stepwise logistic regression analysis.

RESULTS

An elevated uterine resistance index was associated with an increased relative risk for both preeclampsia (relative risk 41.82, 95% confidence interval 5.36 to 326.13) and low birth weight (relative risk 4.65, 95% confidence interval 1.90 to 11.39). A uterine artery notch was associated with an increased risk of preeclampsia (relative risk 52.22, 95% confidence interval 6.82 to 399.70), preterm birth (relative risk 3.21, 95% confidence interval 1.32 to 7.81), and low birth weight (relative risk 4.18, 95% confidence interval 1.64 to 10.66). When the presence of a uterine notch, vaginal bleeding, and level of maternal serum AFP were analyzed by stepwise logistic regression, the presence of a notch was found to be the only significant factor (odds ratio 6.95, 95% confidence interval 1.24 to 39.10) for the development of an adverse outcome.

CONCLUSIONS

Abnormal uterine artery Doppler findings are associated with an increased frequency of adverse obstetric outcomes in women with unexplained elevated maternal serum AFP levels. Abnormal Doppler findings demonstrated high sensitivity for the development of preeclampsia but were less sensitive in predicting other outcomes. The presence of a uterine artery notch is a better independent predictor of adverse outcome than are early vaginal bleeding or maternal serum AFP level.