Use of interphase fluorescence in situ hybridization in third trimester fetuses with anomalies and growth retardation

In the last few years, attention has been focused on the use of interphase fluorescence in situ hybridization (FISH) for prenatal diagnosis with chromosome-specific DNA probes in the second trimester. This technique is accurate, rapid, and detects the most common aneuploidies. We present a preliminary study using FISH technique on uncultured amniotic cells derived from 30 fetuses with ultrasonographic evidence of intrauterine growth retardation (IUGR) in the third trimester. Fifteen fetuses were males and 15 were females. Seven fetuses (23.3%) had abnormal chromosomal constitution: five (18.6%) had trisomy 21, one (2.35%) had trisomy 18, and one (2.35%) showed a mosaic trisomy 18. No abnormalities were detected in the other 23 fetuses. Amniocentesis combined with FISH appears to be a safe, rapid, and accurate alternative to blood sampling in the third trimester, reducing the clinical and emotional stress of the time required to complete chromosome analysis by routine cytogenetics.