RAPID KARYOTYPING IN PRENATAL-DIAGNOSIS - A COMPARATIVE-STUDY OF THE PIPETTE METHOD AND THE IN-SITU TECHNIQUE FOR CHROMOSOME HARVESTING

Rapid karyotyping in the second and third trimesters has important imp lications for the management of pregnancies at risk. From September 19 85 to March 1992, 735 amniotic fluid samples sent to our laboratory fo r rapid karyotyping from 64 different diagnostic centres of the Federa l Republic of Germany were included in a comparative study on harvesti ng for chromosome analysis using the 'pipette method' or the 'in situ' technique. The average time between preparation of the amniotic fluid and verbal notification of the analysed karyotype was 5.41 days. The 'pipette method' needed on average 4.65 days, and the 'in situ' techni que 5.97 days. In comparison with other more invasive techniques avail able for rapid karyotyping such as cordocentesis and placental biopsy, amniocentesis and subsequent chromosome harvesting using the 'pipette method' and/or the 'in situ' technique proved very useful and efficie nt. The overall incidence of chromosome aberrations was 15.3 per cent. The high rate of structural chromosome aberrations and uncommon aneup loidies found in our investigation (12 per cent) indicates that for ra pid karyotyping in the second and third trimesters, conventional cytog enetic techniques cannot be replaced by faster techniques based on flu orescent in situ hybridization on interphase cells in the near future.