Basic ultrasonography is done to Confirm gestational age Determine fetal viability Detect a multifetal pregnancy During the 2nd or 3rd trimester, possibly identify major malformations in the fetal intracranial structures, spine, heart, bladder, kidneys, stomach, thorax, abdominal wall, long bones, and umbilical cord Although ultrasonography provides only structural information, some structural abnormalities strongly suggest genetic abnormalities.