Six years' experience with rapid karyotyping in prenatal diagnosis: correlations between phenotype detected by ultrasound and fetal karyotype.

From September 1985 to March 1992, 804 amniotic fluid samples from 64 different diagnostic centres of the Federal Republic of Germany were sent to our laboratory exclusively for rapid karyotyping. The average time needed for notification of the analysed karyotype was 4.65 days when the 'pipette method' was used for chromosome harvesting and 5.97 days when the 'in situ' technique was used. The overall incidence of chromosome aberrations was 15.3 per cent. Data are presented about the likelihood of abnormal ultrasound findings being caused by chromosome aberrations. These findings include polyhydramnios, oligohydramnios, growth retardation, fetal effusions, neural tube defects, craniofacial defects, heart defects, gastroschisis and omphalocele, gastrointestinal tract defects, urinogenital defects, and limb defects. In future, such data need to contain larger numbers of cases for each week of gestation. This will improve the risk evaluation for each case with abnormal ultrasound findings, which should lead to better management during pregnancy, delivery, and postnatal care for those who require rapid karyotyping.