One of the most common procedures done during pregnancy is an ultrasound exam. Ultrasound scanning involves the use of a hand held probe (called a transducer) that sends out sound waves of a very high frequency, but of very low power. These sound waves bounce off of structures and are reflected back to provide a picture of the baby or pelvic structures. There are many reasons an ultrasound might be ordered by your doctor during the pregnancy. In our practice, an ultrasound is frequently ordered at about 20 weeks. The primary focus of the 20 week ultrasound is to evaluate fetal anatomy, such as the heart, the brain, and the spine. Other information such as placental location, amount of amniotic fluid, and fetal activity can also be assessed. Many, although not all, birth defects can be seen. At present there are no known risks to the baby or the mother with an ultrasound exam. Please remember that this is a medical diagnostic test, so ultrasounds are not ordered without indications and cannot be done strictly for entertainment reasons.