Fetal ultrasound.

Ultrasound provides an opportunity to visualize the fetus and to assess its response to the intrauterine environment. The topic of fetal ultrasound is broad, and whole textbooks have been devoted to areas such as the diagnosis of anomalies. In an effort to provide current practical information, I have focused on the most common clinical questions asked when pregnant women are referred for obstetric ultrasound. We review the diagnoses of oligohydramnios, polyhydramnios, intrauterine growth retardation (IUGR), macrosomia, multiple pregnancy, and common fetal anomalies. Noninvasive assessment of fetal well-being is addressed, along with the use of sonography to refine risk assessment in patients with abnormal antenatal screening tests.