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Current uses of ultrasound in obstetrics.

We have reviewed the current uses of ultrasound in obstetrics. The referring physician must have a clear understanding of the limitations and potential of obstetric ultrasound. The reason for requesting a particular examination should be conveyed to the ultrasonographer. Accurate dating of a particular pregnancy requires an early ultrasonic examination, preferably of the crown-rump length or at least serial BPD measurements so that the growth-adjusted sonographic age can be determined. Placental localization, if the cervical os is encroached upon, is often difficult and may require several scans during the development of the lower uterine segment. The evaluation of fetal growth and assessment of fetal well-being require an in-depth ultrasonic study. A systematic survey of each fetal organ system is necessary to rule out the plethora of anomalies that can now be demonstrated ultrasonically.