Effects of karyotype, gestational age and medium on the duration of amniotic fluid cell culturing

Third-trimester genetic amniocentesis has often been underutilized because of the long period required to obtain results. While fetal cord sampling can be used to obtain rapid karyotypes, its availability is still very limited. With more defined media, the culture duration (CD) for amniotic fluid cells has decreased markedly. We investigated CD as a function of gestational age (GA) and karyotype and found that: (1) there is an inverse correlation of GA and CD; (2) aneuploid karyotypes, translocations and inversions all grow more slowly regardless of GA; (3) since late taps are performed most often on highly suspicious cases, the general impression of late-GA slow growth may be because of a higher likelihood of aneuploidy. Our data thus support increased utilization of third-trimester genetic amniocentesis in selected cases.