Saving One, Dooming Another

Doctors successfully abort an abnormal twin

It was a case that would have tried the wisdom of Solomon. For 18 months, a couple had been trying without success to conceive a child. Then the wife became pregnant with fraternal twins. Because the woman, who had never before given birth, was 40 years old, she underwent amniocentesis in the 17th week of pregnancy. Guided by ultrasound scans, doctors inserted a needle through the woman's abdomen and into the separate amniotic sacs, withdrawing a sample of the fluid that cushioned each of the developing children. The fluid contained cells shed by the fetuses, and these were analyzed for genetic abnormalities. The samples revealed that both twins were boys, but only one showed the normal number of chromosomes. The other had an extra chromosome, which indicated Down's syndrome, a condition characterized by mental retardation and often accompanied by physical defects.

That information left the parents in a quandary. Says a report in last week's New England Journal of Medicine: "The mother desperately wanted to have the normal child but could not face the burden of caring for an abnormal child for the rest of her life." She would have chosen to abort both fetuses rather than continue the pregnancy to term had doctors not told her there was yet a third option: to try to abort only the abnormal twin.

The extremely delicate procedure, which had been successfully carried out only once before, in Sweden in 1978, was performed a year ago by a team led by Dr. Thomas Kerenyi at Manhattan's Mount Sinai Medical Center. The attempt was made in the 20th week of pregnancy, when the fetus weighs about 10 oz. and is about 10 in. long. A series of pictures taken during the earlier ultrasound scanning helped locate the abnormal twin, though not with certainty; Kerenyi put his chances at "much better than 50-50." Doctors then used sound waves to pinpoint the tiny beating heart. On their second attempt, they pierced the heart with a thin needle and withdrew about half the fetus' blood, causing the heart gradually to stop beating. Analysis of the blood later confirmed that the correct twin had been aborted.

The pregnancy continued uneventfully. "The mother looked forward to the birth as a delightful event, and the other aspect didn't bother her," Kerenyi said. Fortnightly ultrasound scans showed the aborted fetus withering away while the live twin grew. Twenty weeks after the abortion, the woman went into labor. She delivered the dead fetus, by this time a paper-thin collection of cells, and a healthy 6-lb. boy.

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