title: Caveats in the sonographic determination of fetal femur length for estimation of gestational age.
abstract: Alterations from the standard conditions under which measurements of fetal femurs are made may alter the estimate of gestational age by up to four weeks. We describe and quantify the errors induced by variations in depth, gain settings, and angle of the femur relative to the US beam. We describe a simple phantom that may be used to help eliminate these sources of possible error.
mesh_terms: D005260:Female; D005269:Femur / Q000196:embryology*; D005325:Fetal Organ Maturity; D005865:Gestational Age; D006801:Humans; D008961:Models, Structural; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D014463:Ultrasonography / Q000379:methods*