Posterior nuchal cystic hygroma [published erratum appears in Clin Perinatol 1990 Dec;17(4):viii] When cystic hygroma is detected antenatally, the prognosis is usually poor, and intrauterine or neonatal death are common. This seems especially true for Turner syndrome (the largest etiologic group associated with cystic hygroma) and the lethal multiple pterygium syndromes. However, some fetuses with Turner syndrome, and also with certain other diagnoses, had a good outcome, and further study of these conditions is required before more definite prognostic indicators and risk figures will be available. Increasing numbers of syndromes are being reported in association with fetal cystic hygroma, and lymphedema may be a common element in their pathogenesis. Mild, short-lived, or otherwise uncomplicated jugular lymphatic obstruction may be a cause of the neck webbing seen in the Noonan, familial pterygium colli, and distichiasis-lymphedema syndromes. With earlier and more widespread fetal ultrasonography, and more sensitive techniques, a greater number of resolving fetal cases may be reported. This may clarify the natural history and provide prospective criteria for the conditions that have better prognoses. The associated conditions include autosomal dominant and recessive genetic traits. Careful ultrasound study for other malformations, polyhydramnios and fetal growth parameters, a fetal karyotype, and, if appropriate, pathologic examination are required to determine the etiology and recurrence risk. The parents should be asked about exposure to alcohol or other agents and should be examined for signs of pterygium colli or Noonan syndrome. If the decision is made to continue the pregnancy, and there is doubt about the natural history and prognosis, multi-disciplinary supervision should include social services, neonatology, pediatric surgery, cardiology, and genetics specialties when indicated. 