Prediction of the small for gestational age twin fetus by Doppler umbilical artery waveform analysis

In 89 consecutive twin pregnancies, monthly Doppler ultrasound measurements were made of the umbilical artery blood flow velocity waveforms of each fetus. In total, 453 Doppler studies were performed. Of the 178 infants, 32 were small for gestational age (SGA); only 24 of the 82 SGA Doppler studies were abnormal, giving an overall sensitivity of the test in the prediction of the SGA fetus of 29% and a positive predictive value of 34%. Furthermore, neither the sensitivities nor the positive predictive values were above 50% in any of the gestational-age intervals individually studied. We conclude that Doppler study of umbilical artery flow velocities is not of much value in the prediction of SGA infants in twin pregnancies, although persistently absent end-diastolic velocities were associated with poor outcome.