Currently between 45 percent and 70 percent of women have an ultrasound some time during their pregnancies. Many U.S. doctors recommend that all pregnant patients receive at least one ultrasound examination usually at about 18-20 weeks. The accuracy of the ultrasound findings depends on the equipment used, the skill of the operator, fetal position, maternal weight, gestational age, and amniotic fluid volume. Ultrasound has become quite accurate in diagnosing many fetal problems. Up to 85 percent of fetuses with spina bifida, enlarged kidneys, or abdominal wall defects can be detected using ultrasound.
Routine ultrasound is likely to miss other fetal problems such as heart defects and club foot.
Even the best ultrasonographers have difficulties seeing all structures in some fetuses. The ultrasound can exclude or confirm that a serious problem is present. If the ultrasound is negative, it may be possible to avoid more invasive testing. Indications for Ultrasound Your doctor may order an ultrasound for many reasons. A sample listing is included below.