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 livebirth rate was 94% (108 of 115) in the nonseptated cystic hygromas, versus only 12% in the septated group. Conclusion: 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.