Ultrasounds: What You Should Know

Who Should Receive One?

Controversy remains regarding the value of the routine prenatal ultrasound for all pregnant women. Many researchers have studied the benefit of routine ultrasounds for every pregnant woman. Some studies have suggested a benefit, while others do not. This contradictory evidence has resulted in conflicting recommendations from different physician groups.

Prenatal ultrasounds are routinely recommended and offered to all pregnant patients in some European countries and in Canada. In the United States, there is not an official recommendation to perform routine ultrasounds in all women; however, many physicians report situations where the routine ultrasound revealed important findings not otherwise suspected.

Currently, between 45 percent and 70 percent of women have an ultrasound some time during their pregnancies. Many US doctors recommend that all pregnant patients receive at least one ultrasound examination, usually at about 18 to 20 weeks.

Reliability of Ultrasounds

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 have their problems detected using ultrasound. However, 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. For example, an elevated maternal serum alpha-fetoprotein (MSAFP) screening test often leads to an ultrasound to examine for spina bifida or other problems associated with an elevated MSAFP. If the ultrasound is negative, it may be possible to avoid more invasive testing.

Prenatal ultrasounds can give you and your doctor important information about you and your baby before delivery. They are safe and relatively easy to perform. The ultrasound can help you prevent or prepare for problems with your delivery or newborn.