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Key Points

  • In most cases, ultrasound is the method of choice for imaging the fetus, and the majority of pregnant women in the United States undergo at least one ultrasound.

  • Sonographer skill and experience play a great role in the accuracy of ultrasound.

  • Ongoing quality assurance is important.

  • There have been exciting advances in the field of prenatal imaging within the past few years including three-dimensional ultrasound and fetal magnetic resonance imaging, and the future holds the promise of great breakthroughs.

  • It is expected that imaging modalities will continue to improve, and it is hoped that techniques utilized in the fields of noninvasive prenatal diagnosis will continue to advance.

  • Accurate prenatal diagnosis of fetal abnormalities improves patient care by optimizing patient counseling and allowing for informed patient and physician decision-making.


The development and practice of fetology has been dependent on advances in the field of prenatal imaging. Without the ability to accurately visualize the structure and well-being of the fetus within its own intrauterine environment, it would not be possible to diagnose or treat the range of abnormalities that can now be addressed by the multidisciplinary fetal health care team. Rapid advances in the technologic basis of two imaging methods—ultrasonography and magnetic resonance imaging (MRI)—have resulted in highly accurate visualization of the fetal anatomy.



Ultrasonography in obstetrics was first introduced in the late 1950s and has since become the method of choice for imaging the fetus. Gray-scale imaging became available in 1973 and resulted in an enhancement of the ability to differentiate the appearance of various organs and tissue interfaces. The advent of real-time sonographic scanning during the 1970s was vital for the accurate visualization of the constantly moving fetus. The subsequent development of higher frequency transabdominal and transvaginal transducers in the late 1970s resulted in vast improvements in the resolution of fetal images and also pushed back the gestational age barrier for accurate prenatal diagnosis into the late first and early second trimesters (D'Alton, 1998).

The 1980s saw innovations in obstetric sonographic technology, including the use of pulsed and color Doppler sonography, which allowed for detailed analysis of fetal perfusion and improvements in the visualization of fetal cardiac anatomy. More recent advances include the development of power Doppler, which displays the strength of a Doppler signal rather than the direction of flow. This technique is useful in fetal imaging for low-flow states and may aid in the definition of fetal tumors and assessing placental function (Ogle and Rodeck, 1998). Three-dimensional ultrasonography is now also available for fetal imaging and has revolutionized the field of prenatal imaging by allowing simple sonographic acquisition of a “block” of fetal tissue (Timor-Tritsch and Platt, 2002). Postacquisition computer processing allows reconstruction of any number of planes through the organ of ...

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