Transvaginal Doppler assessment of fetal intracranial venous flow

Objective: To investigate physiologic blood-flow-velocity waveform patterns of the fetal cerebral Venous system during normal pregnancies by transvagi nal Doppler studies and to evaluate cases with abnormal venous-flow pattern s. Methods: Internal cerebral veins and the three dural sinuses, those of the superior sagittal sinus, vein of Galen, and straight sinus, were examined i n normal cephalic-presenting fetuses of 20-40 weeks' gestation. For analysi s, the venous index was defined as maximum minus minimum velocity divided b y maximum velocity. Different cases with intracranial abnormalities were ev aluated with emphasis on abnormal venous blood-flow patterns. Results: internal cerebral veins had pulsatile patterns with a venous index of 0.22 in 47.6% of fetuses, whereas all fetuses had pulsations in the dur al sinuses. The vein of Galen had a significantly lower Venous index (0.31) than the superior sagittal sinus (0.39) and the straight sinus (0.36), ind icating that the amplitude of the intracranial venous pulsation might incre ase as the now runs from the periphery toward the proximal portion. Signifi cant regression lines of Venous index were obtained, indicating the stabili ty of the pulsation during pregnancy. A fiat pattern of superior sagittal s inus flow was found in three cases of hydrocephalus and one of craniosynost osis. Conclusion: We showed the normal patterns of fetal cerebral venous blood-fl ow velocity and the abnormal patterns which might be associated with increa sed intracranial pressure. Doppler assessment of the intracranial venous sy stem enabled us to evaluate intracranial abnormalities accompanied by incre ased intracranial pressure that might have prognostic clinical importance. (C) 1999 by The American College of Obstetricians and Gynecologists.