Antenatal diagnosis of Patau's syndrome (trisomy 13) including a detailed pathological study of the fetus.

The first ever antenatal diagnosis of Patau's syndrome (trisomy 13) during the 19th week of the pregnancy of a 42-year-old woman is reported. Karyotypes were obtained from amniotic fluid cell cultures established at 17 weeks and the results were confirmed by chromosome banding studies and fetal skin cultures. The pregnancy was terminated by hysterotomy and sterilization was performed at the same operation. A detailed description of the fetus is included and the pathogenesis of arrhinencephaly is discussed. The current status of antenatal screening for chromosome anomalies is presented.