Prenatal diagnosis of dilated cava septi pellucidi et vergae: Associated anomalies, differential diagnosis, and pregnancy outcome

To study the significance of dilated cava septi pellucidi et vergae diagnosed prenatally using ultrasonography. Methods: Sonographic examinations were performed on 11,200 pregnant women. Transabdominal sonographic examinations were done at 24 weeks or later on 3150 pregnant women and transvaginal sonographic examinations were done between 13–17 weeks on 8050 pregnant women.Results: Eight cases of enlarged cava septi pellucidi et vergae were diagnosed prenatally during the second trimester of pregnancy by transvaginal sonography. In only one fetus did dilatation of cava septi pellucidi et vergae disappear during the third trimester. Associated anomalies, three of which were hydrocephalus, were observed in five fetuses. One fetus had chromosomal translocation 11/22 and one was growth-retarded. Pregnancy was terminated in four cases because of associated fetal anomalies or abnormal chromosomal analysis. One of four neonates died of unexplained metabolic acidosis. One neonate demonstrated cava septi pellucidi et vergae communication with the third ventricle and another had mild hydrocephalus on sonographic examination after birth. The three surviving fetuses had normal development during the first months of life.Conclusions: When dilated cava septi pellucidi et vergae are diagnosed prenatally, attention should be paid to the possible presence of associated fetal malformations. When a cyst of cava septi pellucidi et vergae is the only abnormal finding observed, termination of pregnancy is not justified.