Cystic hygroma colli: perinatal outcome after prenatal diagnosis.

Prenatally diagnosed cystic hygroma colli is associated with Turner syndrome, but has been reported with a variety of other conditions. The association with abnormal karyotypes frequently results in a decision to terminate the pregnancy. Information on the natural history of this malformation is thus limited. We reviewed 34 cases of cystic hygroma colli which were diagnosed by ultrasound at a mean gestational age of 17.3 +/- 3.4 weeks. Pregnancy outcome was known for 31 of these cases. The distribution of fetal karyotypes, available for 23 fetuses, was similar to that reported in other series. Only two fetuses, both with an abnormal karyotype, were liveborn at term. Fourteen pregnancies were electively terminated while the remaining 15 cases resulted in spontaneous pregnancy loss. Twenty-six fetuses underwent necropsy which generally confirmed the prenatal ultrasound findings. However, in 9 cases associated anomalies had been missed by the sonogram. Only one fetus with associated anomalies survived to term. Hydrops was common and occurred in most of the spontaneous losses. This series suggests that the prenatal finding of cystic hygroma colli portends an extremely poor prognosis regardless of the karyotype or the presence or nature of associated anomalies. We confirm that karyotypes other than monosomy X are common and that perinatal survival is highly unlikely, especially in the presence of hydrops fetalis.