Routine ultrasound screening in early pregnancy

A normal range for ultrasonically determined fetal biparietal diameter (BPD) was established on 497 normal obstetric patients attending the Flinders Medical Centre, Adelaide. While composite ranges for mean BPD measurements derived from the literature appear to have wide application, the need is apparent to establish a normal range with standard deviations for local institutional conditions and patient populations. With the established normal range as a reference, a consecutive series of 756 patients had ultrasonic fetal BPD measurements performed before 24 weeks' gestation to confirm or establish gestational maturity. It was held that such a screening procedure was justified in view of the high incidence of initial uncertainty in gestational ageing in the population sampled, and the risks of iatrogenic prematurity in both abnormal and normal patients undergoing induction of labour or elective caesarean section.