What is the term for the procedure that uses sound waves to create images of the fetus?

Ultrasonography is the procedure that employs sound waves to create images of the fetus, utilizing high-frequency sound waves that bounce off the fetus and are transformed into visual images. This technique is particularly valuable in prenatal care, as it provides real-time images that can help monitor fetal development, confirm gestational age, detect potential abnormalities, and assess fetal well-being.

Additionally, ultrasonography is non-invasive, poses no radiation risk to the fetus, and is widely accessible, making it a primary tool in the monitoring of pregnancy. In contrast, the other options listed involve different methods of imaging. MRI uses magnetic fields and radio waves, X-rays involve ionizing radiation which is avoided during pregnancy, and CT scans also utilize radiation and are not typically employed for fetal imaging due to potential risks. Therefore, the unique properties and benefits of ultrasonography make it the appropriate term for this procedure.