[Choroid plexus cysts in the 2d trimester--an indication for trisomy 18].

The application of high resolution ultrasound in the prenatal diagnosis enables a detailed differentation of the intracerebral structures in the fetus. In a period of 16 months (Jan. 1990-June 1991) we diagnosed at the "Center for prenatal diagnosis and therapy" at the Charité's Hospital in 14 fetuses among 1800 investigated plexus chorioideus cysts. A rapid karyotyping after cordocentesis was performed in 11 cases. In 3 of them a trisomy 18 could be detected. In one fetus having a normal karyotype we could find besides the cysts multiple structural anomalies. In these 4 cases the termination of pregnancy was performed. In the other 10 pregnancies we could observe a spontaneous regression of the plexus cysts. These results suggest that the prenatal diagnosis of plexus chorioideus cysts is a indication for cytogenetic evaluation in order to detect a trisomy 18.