Fetal cystic hygroma. Cause and natural history.

Fetal cystic hygromas are congenital malformations of the lymphatic system appearing as single or multiloculated fluid-filled cavities, most often about the neck. They are thought to arise from failure of the lymphatic system to communicate with the venous system in the neck. They often progress to hydrops and cause fetal death. In an effort to delineate the cause and natural history of this disorder, we studied 15 consecutive cases of nuchal hygroma detected prenatally by ultrasound. None of the 15 fetuses ultimately survived. Thirteen fetuses were hydropic at the time of diagnosis; nine either died or were bradycardic in utero before abortion; one died a few hours after birth. Eleven fetuses (73 per cent) had karyotypes consistent with Turner's syndrome, and an additional fetus with female genitalia had a 46,XY karyotype. Three fetuses had 46,XX karyotypes, and two of these had multiple malformations. When a hygroma is detected during fetal life, careful sonographic examination of the entire fetus, determination of the fetal karyotype, and an evaluation of the family history are indicated.