Ultrasonic and magnetic resonance imaging of fetal sacrococcygeal teratoma

Objective. To evaluate ultrasonic and magnetic resonance imaging (MRI) and Doppler examination in fetal sacrococcygeal teratoma (SCT), in respect to the postnatal findings and histological type of the rumor. Study design. Nine pregnancies complicated by histologically mature fetal sacrococcygeal teratoma in four cases and by immature/ malignant teratoma in five cases. Transabdominal ultrasonic imaging and Doppler velocity waveforms were recorded during the second or last trimester in all cases, first trimester ultrasound examination was carried out in six cases and last trimester MRI in five cases. These findings were compared with postnatal and operative findings of the children. Results. Ultrasound examination did not reveal intrapelvic parts of SCT, but this was possible by MRI. Velocity waveforms of the tumor arteries were similar in all histological types and the resistance index varied from 60 to 70. The mean gestational age at antepartal diagnosis was 25.2 weeks. Large tumor size with relatively large proportion of solid components was often recognized in cases with malignant/immature histology. Conclusions. Antepartal MRI is useful for examination of fetal SCT, but reliable differentiation of mature and immature SCT is not possible antepartally.