Practicability of ultrasonography for assessing fetal age and weight in early pregnancy.

This study was conducted to evaluate (1) the feasibility and accuracy of the B-Scan technique for measuring biparietal diameter (BPD) in utero, (2) the accuracy of the B-Scan technique for predicting fetal age and weight, and (3) parameters of fetal growth in pregnancies of less than 21 weeks's gestation. Forty-one subjects underwent diagnostic ultrasonography before induction of therapeutic abortion with Prostaglandin F2alpha. Following abortion, fetal crown-to-rump length (CRL), crown-to-heel (CHL), BPD, and fetal weight were measured directly. After 13 menstrual weeks' gestation the BPD could be accurately measured by ultrasound. The relationship of BPD to gestational age and fetal weight and the indices of fetal growth as measured by the CRL and CHL were established. It is concluded that ultrasound is a useful adjuvant to clinical assessment of fetal age and weight in patients form 13 to 21 menstrual weeks' gestation.