Prenatal Diagnosis of Fetal Chromosomes: Evaluation of Mi dtri mester Amniocetesis and Chorionic Villus Sampling in Early Pregnancy *

The congenital anomaly resulting from chromosomal aberrations is serious and well‐known. The incidence in newborn infants is estimated to be 0.5‐1% (WHO). In many cases the mechanism causing a chromosomal aberration is unknown. There appear to be the protective procedures. The procedure that fetal cells obtained by midtrimester amniocentesis could be grown in culture and karyotyped has opened a new area to genetic counseling for chromosomal aberrations. In the past 15 years, 949 pregnant women have undergone amniocentesis in our hospital. Most institutes now employ ultrasonography for examinations of the fetal position and the localization of placenta prior to amniocentesis. The use of this device remarkably reduced the incidence of fetal loss, and the amniocentesis appears to be safe and efficient. A discrepancy has been noted between the rates of chromosomal aberration by diagnosed at amniocentesis and the rates that would be expected from observation in live births. Multiple regression analysis was performed based on the personal informations of mother, providing what may be the risk factors for the recurrence of sibling with a non‐inhetrited chromosomal aberration. Recently, the technique to obtain chorionic villus in early pregnancy for the prenatal diagnosis of fetal defects, now being tested in the United States and Europe, may replace midtrimester amniocentesis within the next few years. The main advantage is that it can reduce the psychologic impact because emotional and physical stresses of a midtrimester abortion are serious problems. There are many possible approaches to obtain chorionic villus sample. Our experience has shown that biopsy forceps inserted via the cervix is most successful. The possibility was discussed that this may be developed in the future for clinical use as an alternative to amniocentesis.