The difference between septated and nonseptated nuchal cystic hygroma in the early second trimester.

OBJECTIVE

To compare nonseptated and septated cystic hygromas in terms of morphologic appearance and prognosis.

METHODS

During a 5-year period, 125 cases of nonseptated cystic hygroma were detected by transvaginal sonography among 7582 sonographic fetal scans (1.6%) in the first and early second trimesters. Twenty-five cases of septated cystic hygroma were detected in the same population. Fetal karyotype abnormalities; sonographic, morphologic, and histologic appearance; and pregnancy outcome were compared between the groups.

RESULTS

Whereas 98% of the nonseptated cystic hygromas were transient, only 44% of the 25 septated cystic hygromas were transient. Six of the 106 cases of nonseptated cystic hygroma that underwent karyotyping were dyskaryotic (5.7%), compared with a 72% (18 of 25) aneuploidy rate in the septated cystic hygromas. Only two cases of hydrops fetalis (1.7%) occurred among the nonseptated cystic hygromas, versus 40% (ten of 25) in the septated cystic hygromas. Fifteen percent of the nonseptated cystic hygromas had associated anomalies (17 of 115) versus 52% (13 of 25) in the septated counterpart. As compared with the septated group, the nonseptated cystic hygromas had a different sonographic, morphologic, and histologic appearance. The live-birth rate was 94% (108 of 115) in the nonseptated cystic hygromas, versus only 12% in the septated group.

CONCLUSIONS

This study confirms our previous suggestion that nonseptated cystic hygromas differ from septated lesions, not only in location and morphologic appearance, but also in prognosis.