High frequency of cytogenetic abnormalities in fetuses with cystic hygroma diagnosed in the first trimester

Objective: The purpose of this study was to evaluate the association between fetal cystic hygroma detected in the first trimester and fetal cytogenetic abnormalities. Methods: Visualization of a prominent (2.5 mm or larger) anechoic or hypoechoic separation of the fetal skin line from the posterior body wall led to the diagnosis of fetal cystic hygroma; presence or absence of septations within the cystic hygroma was documented in each patient. Fetuses with additional structural defects were excluded from this study. All eligible women were offered prenatal cytogenetic studies (ie, chorionic villus sampling, amniocentesis). Results: Cytogenetic studies were performed on all 32 affected fetuses. Fifteen of 32 fetuses (46.9%) had abnormal complements. Septations within the cystic hygroma were demonstrated in 18 fetuses; nine of these had abnormal karyotypes. Of the 12 women carrying fetuses with normal chromosome complements who elected to continue their pregnancies, 11 delivered infants with no evidence of cystic hygroma. Conclusions: Prenatal cytogenetic analysis should be offered to women with fetal cystic hygroma diagnosed in the first trimester. Normal outcome is likely in those showing no chromosome abnormalities.