The validity of screening for small-for-gestational-age and low-weight-for-length infants by Doppler ultrasound.

A prospective blind study assessed the efficacy of Doppler examination of the umbilical arteries (pulsatility index) as a screening procedure for predicting small-for-gestational-age and low-weight-for-length (low ponderal index) infants. Birthweight below the 2.3rd and 10th centile and ponderal index below the 3rd and 10th centile were chosen as 'cut-off' levels. Of pregnant women from our university hospital population, 400 were examined at 28 and 34 weeks gestation. The sensitivity of the test was low, ranging from 16.9 to 41.7% for the different indices. The predictive value of a negative screening test also was unsatisfactory, ranging from 79.6% to 97.9%. It is concluded that a single umbilical artery Doppler examination at 28 or 34 weeks does not satisfy the need in obstetrics for a simple and accurate technique to screen for small-for-gestational-age and low-weight-for-length infants in an unselected obstetric population.