Defining the efficiency of fluorescence in situ hybridization on uncultured amniocytes on a retrospective cohort of 27407 prenatal diagnoses

Rapid prenatal detection of selected numerical chromosomal abnormalities by using fluorescence in situ hybridization (FISH) on uncultured amniotic flu id samples was described six years ago. It allows a very rapid identificati on of selected aneuploidies. We have indexed the results of our 27407 fetal karyotypes obtained by conventional cytogenetics during the last five year s, noting the type of chromosomal abnormality and the reasons for prenatal diagnosis. We have also indexed the chromosomal abnormality regarding the p rognosis of the chromosomal aberations to evaluate the real impact of a non -diagnosis. Within the population of bad prognosis abnormalities, the perce ntage of abnormalities with bad prognosis detectable by FISH is 94.6% for a dvanced maternal age, 85.3% for ultrasonographic anomalies and 86.4% for po sitive maternal screening. The use of FISH alone on our cohort is not a sui table method to diagnose the chromosomal abnormalities. Copyright (C) 2000 John Wiley & Sons, Ltd.