Avoiding a second amniocentesis to corroborate prenatal diagnosis by using refrigerated samples.

OBJECTIVE: This study is aimed to probe the usefulness of refrigerated aliquots of amniotic fluid to be used for fluorescence in situ hybridization (FISH) in order to perform an accurate prenatal diagnosis avoiding the risk related to an additional amniocentesis procedure and the psychological stress to the pregnant woman and her family.

METHODS: Non-cultured amniotic fluid (AF) samples were analyzed by FISH. Such samples were divided into two groups. The first one included fresh collected AF (FCAF, N = 30). The second one included refrigerated samples of AF (RSAF, N = 12) to corroborate uncertain chromosome aberration identification obtained by conventional methods. Sample refrigeration did not exceed 18 days.

RESULTS: No differences were found between groups. In the RSAF group, three cases of chromosomal mosaicismo and seven cases of pseudomosaicism were corroborated. No alteration adjudicated to aberrant chromosomal line presence was found in born children according to genetic specialists' criteria. In the two remaining cases, applied procedure allowed elucidating fetal sex in one case and the origin of a marker chromosome in the other.

CONCLUSIONS: Amniocytes obtained from RAFS are a useful biological material to be assayed by FISH, achieving an accurate prenatal diagnosis and avoiding an additional amniocentesis.