Different Cutoff Values for Increased Nuchal Translucency in First-Trimester Screening to Predict Fetal Chromosomal Abnormalities

Linjuan Su, Xiaoqing Wu, Na Lin, Xiaorui Xie, Meiying Cai, Meiying Wang, Lin Zheng, Liangpu Xu Fujian Provincial Key Laboratory for Prenatal Diagnosis and Birth Defect, Medical Genetic Diagnosis and Therapy Center, Fujian Provincial Maternity and Children’s Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, Fujian, People’s Republic of ChinaCorrespondence: Liangpu Xu; Lin ZhengFujian Provincial Key Laboratory for Prenatal Diagnosis and Birth Defect, Medical Genetic Diagnosis and Therapy Center, Fujian Provincial Maternity and Children’s Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, Fujian, People’s Republic of ChinaEmail ipxiu304@126.com; zlin1536@126.comIntroduction: Increased nuchal translucency (NT) is closely related to an increased risk of chromosomal abnormalities. However, the criterion of increased NT for invasive prenatal diagnosis remains controversial, as the cutoff values are inconsistent among countries. This study was conducted to compare the various cutoff values of increased NT and calculate the incidence of chromosomal abnormalities to determine the predictive ability of these cutoff values in conventional chromosome analysis.Methods: A total of 3223 invasive samples with increased nuchal translucency (NT) or other non-ultrasound indications were collected from singleton pregnant women. Samples with isolated increased NT were divided into five groups based on the NT thickness: 909 samples in the NT ≥ 2.5 mm group, 819 samples in the NT ≥ 95th group, 547 samples in the NT ≥ 99th group, 527 samples in the NT ≥ 3.0 mm group, and 253 samples in the NT ≥ 3.5 mm group; 2301 samples with normal NT were considered as the control group. All five groups were karyotyped and the results were compared. The accuracy of the NT cutoff value for the screening of chromosomal abnormalities was assessed using receiver operating characteristic curve analysis.Results: Detection of all chromosomal aberrations and tr