The role of Doppler velocimetry in the structurally normal second-trimester fetus with elevated levels of maternal serum alpha-fetoprotein.

Umbilical and uterine artery velocimetry was performed in 199 second-trimester pregnancies undergoing sonographic examination for unexplained elevated levels of maternal serum alpha-fetoprotein in order to evaluate the efficacy of Doppler waveforms for the prediction of adverse perinatal outcome. A total of 169 pregnancies resulted in term deliveries of infants with appropriate growth for age, and 30 pregnancies (15%) had adverse outcomes, including preterm delivery, growth retardation and death. The umbilical artery systolic/diastolic ratio was not statistically different in the two groups (3.9 vs. 4.2, p = 0.16). The uterine artery systolic/diastolic ratio was slightly greater in the group with abnormal outcome (5.7) than in the group with normal outcome (3.3), but the difference was not significant (p = 0.11). Forty-six patients had uterine artery waveforms that exhibited an early diastolic notch. Of these, 31 had a grade 1 notch in which the lowest part of the notch was not greater than one half of the diastolic frequency shift. Fifteen patients had a severe or grade II notch in which the deepest part of the diastolic notch was less than half of the diastolic flow. In patients with either no diastolic or grade I uterine artery notch, the incidence of adverse outcomes was 23/184 (12.5%). In patients with a grade II notch, 7/15 (47%) had a poor outcome. The rate of adverse outcome in patients with a grade II notch was more than three times that observed in women without severe uterine notch, yielding a relative risk of 3.4 (95% CI 1.9-6.0). Thus, the presence of a grade II uterine artery notch on second-trimester sonographic evaluation is associated with an increased risk for adverse perinatal outcome over unexplained elevated levels of maternal serum alpha-fetoprotein.