Prenatal ultrasounds: Should you get a “storefront” 4-D ultrasound? Are there risks involved? How do they work and why are they done? What are some false-positives? Why a full bladder? PregTASTIC hosts Dr. Dolores Pretorius, Professor of Radiology at University of California San Diego and Director of Fetal Imaging at the UCSD Fetal Care and Genetics Center and gets the 411 on prenatal ultrasounds.