Fetal aneuploidy diagnosis through rapid fluorescence in situ hybridization (FISH) on uncultured amniocytes

Rapid prenatal diagnostic tests are now increasingly popular, either as a stand-alone test or associated with conventional karyotype. Their main advantages are maternal anxiety relief and low cost. However, the results are available in more than 48 hours from amniocentesis. We present a rapid fluorescence in situ hybridization (FISH) technique, modified to give prenatal diagnostic results in the same day as amniocentesis, using probes for chromosomes 13, 18, 21, X and Y. We tested this technique on 30 amniotic fluid samples in a blinded study. The results were released in maximum 4 hours from the sample collection, including time between laboratories. The method was also validated on cases with trisomy 21 and 18, triploidy and one XYY syndrome. Results of this fast FISH technique were 100% concordant with karyotype. By this method, the results can be released on the same day from amniocentesis, and thus this is a useful method for a one-day stop prenatal diagnosis service. As a stand-alone approach, fast FISH method could be used in a subgroup of patients, where invasive prenatal diagnosis is performed only for an increased risk for aneuploidy, from a positive screening test, but needs karyotype association especially in cases with fetal ultrasound anomalies.