title: A standardized plane for biparietal diameter measurement.
abstract: Biparietal diameter measurement is the most widely accepted means of determining gestational age. However, a standard anatomic plane for performing this measurement has not been established. Three hundred forty-four measurements on 256 patients who gave birth to normal infants were obtained and compared at various cranial levels based on brain anatomy. The results document that use of a standardized plane increases measurement reliability but does not significantly alter variability. We postulate that variability is based predominantly on biologic variation in fetal growth rates rather than on technical errors.
mesh_terms: D002508:Cephalometry / Q000379:methods*; D002552:Cerebral Ventricles / Q000000981:diagnostic imaging / Q000196:embryology; D005260:Female; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D012044:Regression Analysis; D015203:Reproducibility of Results; D012886:Skull / Q000000981:diagnostic imaging* / Q000196:embryology*; D013787:Thalamic Nuclei / Q000000981:diagnostic imaging / Q000196:embryology; D016216:Ultrasonography, Prenatal / Q000379:methods*