Science / Medicine : Ultrasound Reveals Birth Defects

Ultrasound scans can be accurate enough to replace amniocentesis for checking fetuses for spinal abnormalities and other severe birth defects, researchers reported last week in the New England Journal of Medicine.

Amniocentesis, while generally safe, carries a small risk--0.5%--of triggering a miscarriage, whereas ultrasound poses no known risk to the growing fetus. However, doctors often recommend amniocentesis when routine blood tests given to pregnant women show elevated levels of alpha-fetoprotein. While many things can cause this protein to be higher than normal, there is a 1% chance that it means the baby has a defect.

In the study, doctors at Brigham and Women’s Hospital in Boston reviewed the ultrasound pictures of 51 fetuses with spina bifida and related abnormalities that were delivered or aborted at the hospital. In every case, ultrasound had correctly identified the birth defects.

The researchers conclude that if a woman has an elevated alpha-fetoprotein level and a normal ultrasound scan, there is a less than a 0.1% chance that her baby will have spina bifida or a related birth defect.