First-Trimester Cystic Hygroma: Relationship of Nuchal Translucency Thickness and Outcomes

OBJECTIVE: To estimate the relationship between nuchal translucency thickness and abnormal karyotype, major congenital anomaly, perinatal loss, and composite abnormal outcome in fetuses with first-trimester nuchal cystic hygroma. METHODS: We performed a retrospective cohort study of first-trimester fetuses with ultrasound-diagnosed nuchal cystic hygroma collected over a 10-year period. RESULTS: There were 944 first-trimester fetuses with nuchal cystic hygroma. A karyotype abnormality occurred in 54.9% (400 of 729) of fetuses. A major congenital anomaly occurred in 28.8% (61 of 212) of fetuses with a normal karyotype. Perinatal loss occurred in 39% (115 of 295) of fetuses not electively terminated. Overall, an abnormal outcome occurred in 86.6% (543 of 627) of fetuses. After adjusting for potential confounders, every 1-mm increase in nuchal translucency thickness increased the odds of an abnormal karyotype by 44% (adjusted odds ratio [OR] 1.44, 95% confidence interval [CI] 1.29–1.60, P<.001), the odds of major congenital anomaly by 26% (adjusted OR 1.26, 95% CI, 1.08–1.47, P.003), the odds of perinatal loss by 47% (adjusted OR 1.47, 95% CI 1.07–2.02, P.019), and the odds of a composite abnormal outcome by 77% (adjusted OR 1.77, 95% CI 1.15–2.74, P.01). CONCLUSION: First-trimester nuchal cystic hygroma is associated with high rates of karyotype abnormality, major congenital anomaly, perinatal loss, and abnormal outcome. As the thickness of the nuchal translucency increases, the odds of abnormal karyotype, major congenital anomaly, perinatal loss, and abnormal outcome increase.