Level II ultrasound is a type of mid to late pregnancy prenatal ultrasound. There are three levels of prenatal ultrasound for mid- to late-term pregnancy: level I, level II, and level III. Level 1 ultrasound is mainly concerned with the assessment of fetal growth parameters, such as determining fetal size, fetal heart rate and rhythm, assessing placental maturity and amniotic fluid volume, and determining fetal orientation. Level II ultrasound builds on the initial observation of the morphology of the major fetal organs on the basis of level I ultrasound and provides a cursory screening for fetal lethal malformations, including the six major lethal malformations that should be diagnosed between 18 and 24 weeks of gestation, i.e., anencephaly, severe cerebral bulge, severe open spina bifida, severe thoracic and abdominal wall defects, ectopia of the viscera, and lethal short limb anomalies. Regular ultrasounds should be performed during pregnancy.