STANDARDIZATION OF SONAR CEPHALOMETRY AND GESTATIONAL AGE

Abstract

At present a large number of different charts are used for prediction of [human] gestational age from sonar biparietal diameter (BPD). The reasons for these observed differences are presented. Additionally, the usefulness of all these charts is questioned because the mean differences in 7059 BPD derived by the B-scan from 4 large fetal population studies are not significantly different from 0, and BPD obtained by B scan are statistically comparable to gray-scale or real-time BPD if medium gain is used. A chart showing the composite mean BPD values of all 4 studies should be used universally for predicting fetal age. The guidelines of using sonar BPD as an index of gestational age are presented, and the role of the obstetrician in interpreting BPD data is emphasized.