Cytogenetic Diagnosis of Down's Syndrome in Utero

Fetal cells, obtained by amniocentesis from a balanced carrier of D/G chromosome translocation during the 18th week of pregnancy, were analyzed after 22 days of cultivation in vitro. The karyotypes showed a modal chromosome number of 46, with the D/G fusion chromosome characteristic of Down's syndrome. Pregnancy was interrupted by intra-amniotic instillation of hypertonic saline solution. A 700-gm, macerated, male fetus was delivered and showed dermatoglyphic and anatomic changes compatible with the diagnosis made prenatally.