RESUMEN
OBJECTIVE: To evaluate the accuracy of prenatal ultrasonographic diagnosis in fetuses with trisomy 13. MATERIAL METHOD: The present study consisted of all fetuses diagnosed of trisomy 13 and delivered at Ramathibodi Hospital between 1997 and 2006. RESULTS: There were 15 cases of trisomy 13. Twelve cases (80.0%) were detected by prenatal ultrasonographic examination, and 3 cases (20.0%) were missed. Mean maternal age was 31.4 years old. Sixty-six percent were diagnosed in 2" trimester (mean 19.4 weeks). The earliest gestational age for detection was 12 weeks 6 days. The most common abnormal ultrasonographic findings were holoprosencephaly (46.7%), and facial defects (40.0%). CONCLUSION: The accuracy of prenatal sonographic diagnosis in trisomy 13 fetuses was 80%. The most sensitive prenatal ultrasonographic findings in trisomy 13 were holoprosencephaly and facial defects.