Whether a small fetal septum lucidum is important depends on whether other structures or tissues of the fetal brain are normal. If other structures or tissues of the fetal brain are abnormal, it may be more serious and require prompt treatment. Hyaline septum refers to the space between two transparent septa located inside the brain between the fornix and the corpus callosum, with some clear fluid inside. If the septum lucidum of the fetus is small but other structures are normal, it may not be very serious; if the septum lucidum of the fetus is small but other structures are also abnormal, it suggests that it is more serious. It should be noted that if the septum lucidum is small, special attention should be paid to whether the development of the corpus callosum is normal or not, if the development of the corpus callosum is abnormal, it may cause visual impairment of the fetus. If the result of fetal hyaline septum examination is abnormal, it is recommended to consult a doctor in time to make a clear diagnosis with the help of a doctor and carry out targeted treatment or therapy.