Medical Genetics Amniocentesis is normally performed as an outpatient facility An ultrasound examination is normally done immediately before the procedure to evaluate fetal number and via bility, perform fetal biometric measurements establish placental location, and estimate amniotic fluid volumeMedical Genetics Amniocentesis is normally performed as an outpatient facility. An ultrasound examination is normally done immediately before the procedure to evaluate fetal number and viability, perform fetal biometric measurements, establish placental location, and estimate amniotic fluid volume