CHROMOSOMAL-ABNORMALITIES - HOW MUCH CAN WE PREDICT BY ULTRASOUND EXAMINATION IN LOW-RISK PREGNANCIES

We examined the rates of chromosomal anomalies detected by ultrasound investigations for the whole region of Vienna. We evaluated the data o f 250 private offices, 10 clinics for Obstetrics and Gynecology, and o ne university Department of Prenatal Diagnosis and Therapy during the period from January 1990, to July, 1991. The study group consisted of low-risk patients, since cases where prenatal karyotyping has been per formed for other reasons than sonographic findings (for example, mater nal age) were excluded from the study. An overall detection rate of 53 .7% was found for the region. Structural malformations of fetuses (41. 5%) were the most prominent factors leading to the diagnosis of chromo somal abnormalities. In addition, detection rate of trisomy 21 (17.6%) by prenatal ultrasonography was found to be significantly lower compa red to all other chromosomal abnormalities in our study (50 to 100%).