Procedure, part 2
The transducer emits inaudible sound waves, which fan out as they travel through your abdomen. When they hit dense structures like the fetus and the wall of your uterus, the sound waves bounce back to the transducer and are translated into a visual image by the computer.
Update Date 3/11/2014
Updated by: Susan Storck, MD, FACOG, Chief, Eastside Department of Obstetrics and Gynecology, Group Health Cooperative of Puget Sound, Bellevue, WA; Clinical Teaching Faculty, Department of Obstetrics and Gynecology, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.