Diagnostic ultrasonography.

The use of diagnostic ultrasound has contributed to the evaluation of the fetal condition in two ways--the detection of fetal abnormality and the assessment of fetal growth and development. Routine early pregnancy scanning enables most major structural anomalies to be detected and provides accurate gestational dating. Maternal serum alphafetoprotein screening complements ultrasound in identifying abnormalities, and may also be an indicator of a growth problem in later pregnancy. In high-risk pregnancies, or when growth retardation or acceleration is suspected, abnormalities should always be considered and investigations should include karyotyping. Fetal growth may be assessed by multiple parameters, including measurement of fetal head, trunk, limbs, and amniotic fluid volume, in addition to grading of the placenta. Fetal responses to stimulation can be visualized and quantified. No single parameter may be used alone to predict fetal outcome, but by using this multiple-parameter approach, contributing to a biophysical profile of the fetus, the outcome of pregnancy may be predicted with greater accuracy.