[Clinical study on fetal encephalic fluid].

OBJECTIVE: To discuss the clinical significance of fetal encephalic accumulated fluid revealed by prenatal ultrasonography.

METHODS: Prenatal ultrasonography was performed on 8426 women at more than 20 weeks' gestation. Totally 150 women with fetal encephalic accumulated fluid more than 5 mm were included in this study. The changes of fetal encephalic accumulated fluid and the associated anomalies were observed regularly every 2 weeks until delivery. The live infants were followed up regularly.

RESULTS: The incidence of fetal encephalic fluid was 1.8%, including 72 cases with fluid in the fetal anterior or posterior cornu of unilateral ventricle, 46 cases with accumulated fluid in fetal posterior fossa, 32 cases with fluid in more than 2 sites. Generally, the accumulated fluid in fetal encephalus was first diagnosed at 17 - 40 gestational weeks, with a median of (26 +/- 5) weeks. Most of them were found between 29 - 32 gestational weeks (63 cases, 42.0%), and the maximum amount of accumulated fluid was also found between 29 - 32 weeks (70 cases, 46.7%). Spontaneous regression of intracranial fluid could be seen in 111 fetuses (74.0%). The period of fluid regression ranged from 29 to 40 weeks of gestation, of which the average gestational week was (36 +/- 2) weeks. Additionally, the most frequent period of regression was in the first two thirds of the three trimesters of pregnancy. The incidence of defected infants was 3.8%, 10.2% and 67.4%, respectively, when the amount of accumulated fluid was less than 10 mm, 10 - 14 mm and more than 15 mm. And the accumulated fluid in more than 2 sites was also a risk factor of defected fetuses, with an incidence of 60.0%.

CONCLUSIONS: Most cases could be diagnosed between 29 - 32 gestational weeks, and the maximum amount of accumulated fluid is also observed in this period. The more fluid in fetal encephalus, the more sites the fluid distributed in, the more defected fetuses or infants would be observed. So in cases of more than 15 mm of fluid, or accumulated fluid in more than 2 sites, anomalies should be observed extremely carefully.