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