Karyotyping from uncultured human trophoblast in the first trimester of pregnancy.

Chorionic villi were sampled by transcervical aspiration after ultrasonic localization of the chorion frondosum. Sampling was successful in 82 of 98 women. Subsequent karyotyping of the chorionic material was done by the modified Evans method. Mitoses of reasonable quality were obtained providing an easy cytogenetic diagnosis from human cytotrophoblast. A second trimester chorionic plate biopsy and direct karyotyping in case of severe oligohydramnios and malformed fetus revealing numerical (45, XO) chromosomal abnormality is also reported.