Advertisement

Focus on Pregnancy : The Pregnant Pause : With more choices in prenatal testing, women and their doctors must discuss and carefully consider which test is right for them.

September 06, 1999|SHARI ROAN | TIMES HEALTH WRITER

When Carrie Yoshida was born in 1957, the doctor who delivered her looked at the newborn's deformed left hand, shrugged and told her startled parents: "A birth defect."

That was the extent of the explanation for Carrie's hand, in which several fingers were fused together and resembled a cat's paw. After a series of plastic surgeries to separate the fingers, Yoshida went on to play volleyball and teach art.

But when the Redondo Beach woman became pregnant at age 41 last year, the "birth defect" explanation seemed wholly inadequate. Carrie and her husband, Wendall, wondered if the problem could be passed on to their baby.

After providing a genetic counselor with an extensive health history, Carrie underwent a procedure known as chorionic villus sampling (CVS), in which a small piece of tissue from the placenta is removed via needle to examine the baby's genes and look for genetic diseases. And midway through her pregnancy, Carrie had an ultrasound, which clearly showed a baby with 10 perfect fingers and toes.

"If my child had [the hand defect], I felt that wasn't a reason to terminate the pregnancy. But I wondered if the child might have another problem" related to the hand abnormality, says Carrie, who gave birth to a son, Cole, on July 29. "I think I would have been very stressed if I had not found out."

Clearly, the Yoshidas benefited from appropriate use of prenatal testing. But, after a decade of advances in prenatal screening and genetic testing, doctors are not always in agreement about which tests are best suited for particular patients.

"The only people who are certain about what should or shouldn't be offered are the plaintiffs' lawyers," Detroit obstetrician Marc Evans says wryly, noting the frequent lawsuits that are filed by parents whose baby is born with an abnormality that they think should have been detected during pregnancy.

According to Evans, a leading authority in prenatal testing and a professor of genetics at Wayne State University in Detroit, the field of prenatal testing is shifting daily, with new advancements on the horizon and once-popular practices falling out of favor. These changes mean that pregnant women and their partners no longer can depend on the advice of friends who gave birth three or four years ago.

Couples need to do their homework and have detailed discussions with their doctors or other health care professionals about their options for prenatal testing, experts advise. Here is an update on the major tests and issues surrounding them.

Ultrasound

In a darkened, closet-sized room in the offices of Dr. Lawrence Platt at Cedars-Sinai Medical Center in Los Angeles, a video monitor displays the three-dimensional image of a fully formed fetus seemingly floating in space.

The astonishingly clear images look as if they were taken with a video camera tucked in the mother's uterus. To an untrained eye, the baby looks as it should. But, in fact, there are problems, Platt says.

The fingers are too short and chubby. The chin is pulled back into the face. The forehead is very flat. The fetus, in fact, has a major chromosomal malady called trisomy 18, which will likely result in death shortly after birth.

The video of this baby illustrates both the promise and drawbacks of the latest sensation in prenatal testing, 3-D ultrasound. By viewing the fetus in three dimensions, doctors can more accurately discover or confirm problems. However, expectant parents may find it extremely hard to reconcile the exquisite pictures with the knowledge that this baby will be born gravely ill.

"It's a great advance in technology. But it shouldn't be abused. We're still learning the power of this technology," says Platt, chairman of obstetrics and gynecology at Cedars and a leading researcher in ultrasound technology.

Ultrasound technology creates pictures of the uterus and baby with sound waves. The test is considered very safe, although studies have never established with certainty that the procedure is not without risk for the mother or baby.

With 3-D ultrasound, the test is performed the same way as conventional ultrasound, except that the computer gathers images from a third angle. Thus, a 3-D picture creates a feeling of depth and allows the doctor to view the fetus from different angles. In contrast, 2-D ultrasound requires the doctor to use his or her imagination to complete a picture of the baby.

The advanced ultrasound technique--whose $500 cost is usually covered by health insurance if the procedure is "medically necessary"--is not intended for use in all pregnancies, doctors say. Studies have shown that the procedure is superior in diagnosing abnormalities of the face, brain, fingers and feet, skeleton and lower extremities.

The technology also requires experienced operators, Platt says. Typically, only large, academic medical centers in the United States have 3-D ultrasound and are using it only in cases where an abnormality has already been detected.

Advertisement
Los Angeles Times Articles
|
|
|