Detecting heart defects prenatally.

In the United States, fewer than 1 in 10 heart defects in children are detected before birth. If pregnant women were tested by ultrasound later in their pregnancy than the first trimester, the odds of finding such a defect would improve greatly, as would the survival chances of a baby with a congenital heart problem, says Mary Jo Rice, a cardiologist at Oregon Health Sciences University in Portland. Rice spoke at a seminar in Portland sponsored by the American Heart Association in July.

First-trimester ultrasound examinations are typically done to predict birth date and to check overall development of the fetus, but they cannot get clear images of its tiny heart. Rice estimates that one-third of pregnant women in the United States do not get an ultrasound at all.

Heart defects occur in 8 of every 1,000 babies. Before birth, the baby receives oxygenated blood from its mother, but once the baby is born, its heart takes on this task. A structural defect can be fatal at this point. Prenatal detection would allow a mother to give birth at a cardiac center, where a team of heart specialists could be ready should an operation on the newborn prove necessary, Rice says. Early detection could also help prepare the family for the emotional strain, expense, and logistical problems of surgery on the newborn. "We need to optimize delivery to maximize survival," says Rice.

Some heart problems could even be treated prenatally. In cases of fast heartbeats, for example, doctors can give medicine to the mother or the fetus directly through the umbilical vein. Rice advocates training ultrasound technicians to check images for cardiac irregularities.

Although some families--those with a history of heart disease or diabetes, for example--are at greater risk than others, 60 to 70 percent of babies born with heart defects had no risk factors, Rice says. The only way to find out whether such babies have a defect is through ultrasound screening.

In Great Britain, where ultrasound is routine at 18 to 20 weeks, 80 to 85 percent of heart defects are detected before birth. The detection rate in the United States is only 8 to 10 percent, Rice says.

The point is to pick a time in gestation, at 18 to 20 weeks, when we can get good pictures of the heart," says Henry Sondheimer, a cardiologist at Children's Hospital at the University of Colorado at Denver.