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Placental sonolucency and pregnancy outcome in women with elevated second trimester serum alpha-fetoprotein levels.

BACKGROUND AND PURPOSE
Women with unexplained elevation of serum alpha-fetoprotein (AFP) are at increased risk for adverse pregnancy outcomes, including small for gestational age neonate, preterm labor, abruptio placentae, preeclampsia, intrauterine fetal death, and congenital malformations. This study investigated the association between placental sonolucency, elevation of maternal serum AFP, and pregnancy outcomes.


METHODS
Singleton pregnancies (n = 168) with second trimester serum AFP level >/= 2.0 weight-adjusted multiples of the median (MoM) were recruited as the study group. Women with second trimester serum AFP level between 0.4 and 2.0 weight-adjusted MoM (n = 150) served as controls. A maternal Kleihauer-Betke stain was obtained for all participants. All participants were prospectively evaluated and the pregnancy complications were assessed by chart analysis after delivery.


RESULTS
Compared with control subjects, women with placental sonolucent areas were not at increased risk for pregnancy complications, while women without sonolucent areas had higher risk of pregnancy complications. Singleton pregnancies with elevated serum AFP level had increased incidence of feto-maternal hemorrhage when placental sonolucency was observed.


CONCLUSIONS
Our data suggest that feto-maternal hemorrhage may be the major factor contributing to elevated maternal serum AFP levels in pregnancies carrying placental sonolucencies. Screening for pregnancies with both elevated serum AFP and placental sonolucencies would help to identify the low-risk cases and facilitate cost-effective obstetric management.