Significance of septa in first trimester increased nuchal translucency thickness

The objective of this study was to investigate perinatal outcome in cases of increased nuchal translucency (NT) with or without cystic hygroma (CH), and to determine whether first-trimester CH engenders a greater risk than simple increased NT. In this retrospective study, data from singleton pregnancies in which fetal NT was found to be 3 mm or more at the 11 + 0 to 13 + 6 weeks scan were reviewed. Cases were classified into two groups, namely 'CH' and 'increased NT'. Of the 76 cases with increased NT, 30 (39.4 %) presented with CH. NT measurement was significantly higher in the CH group (7.25 vs. 3.5 mm, p < 0.001). Abnormal fetal karyotype, major chromosomal anomalies in chromosomally normal fetuses, and adverse outcome were significantly more frequent in the CH group as compared with the increased NT group (p = 0.019, p = 0.021, and p = 0.001, respectively). Regression analysis revealed that NT thickness was the only significant variable in the prediction of chromosomal defect and/or major congenital anomaly (OR 2.05, 95 % CI 1.23-3.42, p = 0.005). Cystic hygroma results in poorer outcome due to higher NT measurement, and the thickness of NT rather than the presence of septa should be the mainstay of prenatal counseling in cases of increased NT in the first trimester.