Comparative analysis of ultrasonographic methods of gestational age assessment

Measurement of crown-rump length (CRL) is widely accepted as the most accurate method of gestational dating. The statistical accuracy of growth-adjusted sonographic age (GASA) determinations has been demonstrated to be similar. Ninety-six patients were prospectively examined by use of serial ultrasonography, and findings were evaluated to correlate CRL with a single biparietal diameter (BPD) obtained between 20 and 24 weeks of gestation, with GASA, and with accurate maternal dates. Growth-adjusted sonographic age was shown to be not as accurate as CRL and no more accurate than a single BPD obtained between 20 and 24 weeks or reliable maternal dates.