Rate of chromosomal aberrations in prenatally detected hydrops fetalis and hygroma colli.

Chromosome analyses were carried out in a series of 775 fetuses with morphological abnormalities diagnosed by ultrasound. Among these cases, 57 demonstrated non-immune hydrops fetalis with hygroma colli (group 1) and a further 116 non-immune hydrops fetalis without hygroma colli (group 2). Different chromosome abnormalities were found in 54.5% of cases of group 1 where chromosome analyses could be performed, and in 27.6% of cases of group 2. The most common aberrations were monosomy X and trisomy 21.