Sonographic determination of gestational age

Objective.To review current evidence regarding sonographic determination of gestational age.Methods.We reviewed current and available data to evaluate optimal methods of gestational age determination.Results.First trimester estimates of gestational age based on crown-rump length and second trimester estimates of gestational age based on composite biometry are very accurate with an absolute error of less than 5 days in the first trimester and 7 days in the second trimester in most cases.Conclusion.Ultrasound is an accurate and useful modality for assessment of gestational age in the first and second trimester of pregnancy and, as a routine part of prenatal care, can greatly impact obstetric management and improve antepartum care.