Very rapid prenatal karyotypic analysis using uncultured fetal nucleated red blood cells

Prenatal cytogenetic diagnosis is routinely performed by analysing fetal cells obtained by amniocentesis, chorionic villus sampling (CVS), or percutaneous umbilical cord blood sampling (PUBS). CVS and PUBS can provide diagnostic results more rapidly than amniocentesis because cells obtained by CVS or PUBS divide spontaneously without the need for culture techniques, thereby permitting karyotypic analysis of small numbers of cells arrested in growth during metaphase. Specifically, direct analysis of cytotrophoblastic cells obtained by CVS and nucleated fetal cells, obtained by PUBS has been shown to provide sufficient numbers of metaphases and thus provide consistent, rapid, and reliable prenatal cytogenetic diagnoses. Cytogenetic diagnosis by direct analysis of these cell types can be obtained within 24-48 h. However, clinical situations may arise that necessitate even more rapid results; recently, the management of two patients required fetal cytogenetic diagnostic results to be available within several hours. We sought to determine whether rapid karyotypic analysis was feasible by analysis of uncultured fetal nucleated red blood cells obtained by PUBS.