Basic Ultrasound

The “basic” obstetrical sonogram is a routine prenatal screening ultrasound scan that is typically performed between 18-22 weeks of gestation using a trans-abdominal probe. A basic scan does not require an extensive anatomic analysis of the mother and fetus, and the minimal elements of evaluation include:

• Uterus and cervix
• Adnexal evaluation, when feasible
• Fetal number
• Presence of cardiac activity and movement
• Fetal presentation
• Qualitative assessment of amniotic fluid volume
• Placental location and number of cord vessels
• Gestational age assessment using several fetal measurements
• Third trimester estimated fetal weight
• Anatomic survey of fetal organs: cerebral ventricles, posterior fossa with cerebellar diameter, four-chamber view of the fetal heart, stomach, kidneys and bladder, cord insertion site and ventral wall and spine