Transvaginal sonography of the fetal brain: detection of abnormal morphology and circulation

To analyze the incidence, transvaginal detection age, sonographic appearance, clinical course, and outcomes of pregnancy in cases with abnormal fetal brain structure and/or circulation, and to evaluate the clinical significance of sonographic abnormalities.

Serial observation of the fetal brain and intracranial Doppler assessment by transvaginal approach at four-week intervals were performed in 306 singleton fetuses from the first trimester and 13 referral cases at our ultrasound units from January 1996 to December 1997. Detection of abnormalities was followed by subsequent serial scans every one or two weeks.

Morphological abnormalities were found in 66 cases: open neural tube defect (9 cases), disorders of prosencephalic development (2), ventriculomegaly with cerebellar hypoplasia (1), hydrocephalus (1), craniosynostosis (1), unclassified brain anomaly (1), brain atrophy (1), isolated choroid plexus cysts (19), choroid plexus cysts with cerebellar hypoplasia (2), lateral ventricular asymmetry (26), and subependymal cyst (3). Chromosomal aberration was found in 4 cases. Artificial abortion was performed in 10 cases and fetal demise occurred in 2 cases. Isolated choroid plexus cysts, isolated ventricular asymmetry and subependymal cyst were not clinically significant. Two abnormal flow patterns of superior sagittal sinus, sharp doubled pulsatile pattern, and disappearance of normal pulsatile pattern were found in different situations.

Serial transvaginal observation of the fetal brain provided evidence of hitherto unreported intracranial abnormalities: subependymal cyst, craniosynostosis, medullary kink in Chiari malformation, brain damage, and abnormal venous flows. Venous flow assessment may be of great potential in predicting fetal neurological well-being.