Gray scale measurement of biparietal diameter

Abstract

Fetal biparietal diameter measurements were obtained simultaneously by gray scale and bistable ultrasonography. The bistable presentation was measured from leading edge to leading edge, while the gray scale presentation was measured from leading point to leading point and middle to middle of the band of echoes defining the fetal head. Statistical analysis of 50 patients demonstrated good reproducibility of the biparietal diameter measurement by each method and intraobserver variation fell well within the acceptable range. In all but one patient differences in measurements between observers and measurement methods were trivial and of no clinical significance. In the patients in whom there was a statistically significant difference, the variability was from 1 to 2 mm with the exception of one patient in whom the variability was about 4 mm.