The formation of fetal cerebral effusion is mainly due to obstruction of fetal cerebrospinal fluid reflux, and obstruction of cerebrospinal fluid reflux is often a sign of abnormal fetal cranial development or chromosomal abnormalities. It is recommended to improve the fetal cranial MRI examination to exclude the possibility of cranial developmental abnormalities in the fetus. In addition, fetal cerebral effusion often indicates a widened lateral ventricle on ultrasound. Generally, in the middle and late pregnancy, if the fetal lateral ventricle is larger than 10 mm, it indicates a widened lateral ventricle. If necessary, amniocentesis should be performed for prenatal diagnosis depending on the maternal age and whether there are high-risk factors.