Outcome of cystic hygroma in fetuses with normal karyotypes depends on associated findings.

Objective: To determine the associated diagnostic findings which are linked with adverse fetal outcome in nuchal cystic hygroma.

Study Design: Based on a series of 32 cases, we determined the sonographic morphology of the hygroma, associated structural anomalies, karyotypes and autopsy findings. Intrauterine fetal death, spontaneous abortion and abnormal karyotypes were assigned as adverse outcome parameters.

Results: The mean gestational age at diagnosis was 14.4 weeks (range 10-21). There were 18 nonseptated and 14 septated hygromas. Besides hygroma, associated sonographic detectable structural anomalies were observed in 17 cases (53.1%). The greatest number of associated sonographic anomalies were hydrops (31.3%), generalised skin oedema (6.3%) and pterygium colli (6.3%). Cytogenetic analysis revealed an abnormal karyotype in 13 of 26 (50%) invasive procedures. Turner syndrome and Trisomy 18 (both 15.4%) were the most frequent cytogenetic abnormalities. Autopsy was performed in 24 cases and 16 cases (66.7%) had an associated autopsy finding to hygroma colli. The most frequent associated autopsy findings were limb and craniofacial anomalies (both 25%). Only 3 (9.4%) mothers gave birth to healthy newborns. The overall fetal adverse outcome rate was 68.8% (22 cases).

Conclusions: Fetuses with NCH are at high risk for adverse outcome and detailed prenatal diagnosis including invasive procedures should be offered. According to the presented autopsy findings, to determine fetal outcome in NCH cases with normal karyotypes, detailed sonography should be concentrated beside the exclusion of fetal heart defects and existence of hydrops fetalis, on the skeletal, urogenital and craniofacial anomalies, as these might cause severe morbidity.