Fetal cystic hygromas: further insights into their natural history

The authors report their experience with 17 cases of cystic hygroma diagnosed in utero over a period of 6 years and followed to early infancy. Attempts were made to determine which ultrasonographic features were significant in predicting the outcome of this condition. The intrauterine course of the 6 fetuses with a normal karyotype and the 11 fetuses with Turner's syndrome or another form of aneuploidy was analysed to determine whether the size of the hygroma or the presence of septation or nonimmune hydrops could be used to predict the eventual outcome of the pregnancy. An association between the presence of septation and outcome was not demonstrated, but there was a strong association between septation and aneuploidy. Septate lesions were present in 6 of the 10 fetuses with Turner's syndrome and only 2 of the 6 fetuses with a normal karyotype. In this series the most significant features indicating a favourable outcome were the size of the hygroma (no fetus in which the hygroma had a diameter greater than 6 cm survived) and the change in size from the time of diagnosis until 24 weeks' gestation. Of the three fetuses in which the hygroma did not regress by 24 weeks, two died in utero.