Prenatal cytogenetic diagnosis by amniocentesis before 15 weeks' gestation.

Three hundred and ten early amniocenteses before 15 weeks' gestation, including one set of triplets and four twins, were performed for prenatal cytogenetic diagnosis. There was a 100% success rate in obtaining amniotic fluid and 99.4% success rate in achieving amniotic cell cultures. The mean time from amniocentesis to cell harvest by the in situ culture method was 11.3 days. A total 13 abnormal fetal karyotypes were diagnosed. The total fetal loss rate (spontaneous abortion, elective termination and late loss) was 4.5%, while miscarriage within two weeks after amniocentesis occurred in three cases (1%). Early amniocentesis combined with in situ cell culture is a safe, rapid and effective technique for early prenatal cytogenetic diagnosis.