To explore prenatal MRI diagnosis and perinatal outcome of fetal congenital hydrocephalus (CH) in Beijing in recent 6 years.

From January 2015 to December 2020, a total of 468 fetuses and newborns with CH included into Beijing Birth Defects Monitoring Network were selected as the study subjects. The diagnosis of CH and perinatal death data of intrauterine and within 0-6 d after birth were analyzed retrospectively. The perinatal mortality of children with isolated CH were compared between prenatal diagnosis and postnatal diagnosis by chi-square test. The procedure followed in this study was in line with World Medical Association Declaration of Helsinki revised in 2013.

①The prevalence of CH fetuses and newborns within 0-6 d after birth from 2015 to 2020 in Beijing Birth Defects Monitoring Network was 3.57×10^-4 (468/1 310 025). The prenatal diagnosis rate of 468 children with CH was 97.44% (456/468). The median gestational age when CH was detected in pregnancy was 24 weeks, and the gestational age ≥28 weeks at the time of diagnosis of CH accounted for 26.53%(121/456). ② Among 456 prenatal diagnosed cases, 56 cases were examined by prenatal ultrasound combined with MRI, accounted for 12.28%(56/456). Among those 56 cases, results of MRI were consistent with ultrasound diagnosis in 40 cases, and 16 cases were supplementary diagnosed specific types of intracranial malformations. ③ Among 105 children with isolated hydrocephalus of gestational age ≥28 weeks, except 49 cases were taken therapeutic induction labortion measures, the perinatal mortality rate of another 56 cases was 14.29%(8/56). The perinatal mortality rate of prenatal diagnosis and postpartum diagnosis of isolated hydrocephalus were 12.24%(6/49) and 28.57%(2/7), respectively, and there was no significant difference between them (χ²=0.33, P=0.564). The perinatal mortality rate of prenatal ultrasound diagnosis and prenatal ultrasound combined MRI diagnosis of isolated hydrocephalus were 11.63%(5/43) and 16.67%(1/6), respectively, and there was no significant difference between them (P=0.564).

Prenatal MRI has supplementary diagnostic value for intracranial malformation than prenatal ultrasound in children with CH.