ABSTRACT
PURPOSE: To evaluate the NT in the first trimester associated with fetal chromosomal abnormality, fetal structural abnormality and adverse pregnancy outcome. METHODS: From Mar. 1993 to Dec. 1997, 133 cases of increased NT were reviewed retrospectively. All these fetues were taken a karyotyping and/or a high resolution ultrasonography for associated anomaly. The NT was measured by transvaginal ultrasonography(TVS) and transabdominal ultrasonography(TAS) if difficulty was encountered with TVS in the period of the 10th-14th week of gestation. The increased NT is approved when it is over 3mm. RESULTS: Of these 133 cases, 102 cases(76.7%) revealed normal outcomes and 31 cases(23.3%) revealed abnormal outcomes such as chromosomal abnormality, structural abnormality and adverse pregnancy outcome, The mean value of NT was 3.44+/-0.68mm in the normal group and 4.93+/-2.70mm in the abnormal group, respectively. The chromosomal abnormalities were found in 16 of the 31 cases: nine Down SD, two Patau syndrome, one Tuner synrome, one triploidy, one 46, XX,i(18q), one 47,iso(Xp)/46,XX one confined placental mosaicism. In 12 cases of the 31 cases, the structural anomalies were detected. Of these 12 cases, 3 cases were eventually developed to cytsic hygroma, 3 cases were cardiac anomaly, 3 cases were renal anomaly, 1 case was congenital diaphragmatic hernia, 1 case was skeletal dysplasia and 1 case was suspected syndrome. The adverse pregnancy outcome such as intrauterine growth restriction, intrauterine fetal death and preterm labor was revealed in 3 cases. In the cases of NT over 7mm, the result was 100% abnormal outcome. CONCLUSION: Increased NT in the first trimester could be a highly efficient the predictor for detection of chromosomal abnormality, structural anomaly and adverse pregnancy outcome.