The predictive value of abnormal ultrasonographic finding for fetal trisomy in the second trimester / 대한산부인과학회지

ABSTRACT

OBJECTIVE: The purpose of this study is to evaluate obstetrical characteristics related to fetal trisomies and to survey the predictive value of abnormal second trimester ultrasonographic findings for fetal trisomies. METHODS: We reviewed the medical records of 3,023 patients who had fetal karyotyping performed between May 1989 and May 2005, and then retrospectively examined 71 cases of trisomies diagnosed prenatally. All patients were classified into three groups according to indications of fetal karyotyping such as positive triple test result, maternal age older than 35 at delivery, and abnormal ultrasonographic findings and we compared the obstetrical features and positive predictive value of each indication. RESULTS: Thirty two cases (39%) of total trisomies had abnormal ultrasonographic findings. Abnormal ultrasonographic findings were significantly more common (16 cases, 76%, P=0.001) in fetuses with trisomy 18 compared to the other trisomies. Structural anomalies in fetuses with trisomy were usually detected in late second trimester. The positive predictive value of abnormal ultrasonographic findings was 3.0% (elderly woman; 1.4%, positive triple test; 1.7%) in trisomy 21 and 6.3% (elderly woman; 1.6%, positive triple test; 1.8%) in both trisomy 21 and 18. CONCLUSION: The positive predictive value of abnormal ultrasonographic findings for diagnosis of fetal trisomy is higher than the other indications for fetal karyotyping. In addition, screening of trisomy 18 with an ultrasonography may be still more important because the majority of fetuses with trisomy 18 show various congenital anomalies.