The role of fetal karyotyping from unconventional sources

Objective: Our purpose was to determine whether fetal specimens, including pleural, ascitic, pericardial, facial, and cystic hygroma fluid or urine, are suitable sources for accurate chromosomal analysis. Study Design: Thirty-nine samples of fetal fluid (pleural, n=11; ascitic, n=5; pericardial, n=1; lung cyst, n=1; facial cyst, n=1; cystic hygroma, n=7; and urine, n=13) were cultured and analyzed with standard cytogenetic techniques for lymphocytes or amniotic fluid. These samples were obtained as part of the routine obstetric investigation and management. Conventional backup samples were also obtained. Results: Karyotyping was successful in 34 of 39 samples. Cells were harvested from all pleural samples, three ascitic samples, and one hygroma fluid sample in 2 to 4 days and from 11 urine samples, one ascitic sample, and the remaining six hygroma samples in 7 to 11 days. Five cultures were unsuccessful. Samples with high lymphocyte counts yielded results as quickly as fetal blood. Conclusion: The use of “alternative” samples of fetal fluids for karyotyping may be considered when amniotic fluid or fetal blood is difficult to obtain. In selected cases this approach avoids the unnecessary risk of additional invasive procedures solely to obtain a karyotype.