Selective Birth in Twin Pregnancy with Discordancy for Down's Syndrome

AMNIOCENTESIS for genetic evaluation is now a well-established prenatal diagnostic procedure. The discovery of twins at the time of amniocentesis, however, necessitates additional measures, and in the event of detection of discordancy for an abnormality, it poses a challenging problem. In 1975, Bang et al. reported the first successful amniocentesis and karyotyping in twins. They also forecast the inevitable dilemma: "One unsolved question is the consequence of finding one abnormal and one normal fetus."1 At least five recent articles have described cases in the mid-trimester in which one fetus had a major congenital malformation and the other one was normal. . . .