[Fetal plexus cysts. An indication for prenatal karyotyping].

From March 1988 to September 1990, 1844 patients (pregnant women) were sonographically examined following a pregnancy monitoring programme and for further diagnostic clarification of unclear sonographic patterns. The ultrasound examinations were carried out with a 3.5 Mhz convex transducer, and by pregnancies before the 16th week with a 5 Mhz vaginal transducer (Toshiba SSA 250 a), respectively. In 13 cases (0.7%), foetal chorioidal plexus cysts were found; in 6 of them they occurred unilaterally and in the other 7 bilaterally. In general, most of the cases were diagnosed between the 13th and 22nd weeks of pregnancy. All unilateral cysts appeared transitorily, were of small size and receded by the 24th week of pregnancy. From the 7 patients with bilateral plexus cysts, 4 foetuses showed no signs of anatomical abnormalities. In the other 3 foetuses, it was possible, to recognise further anatomical abnormalities, when performing ultrasound i.e. 2 of them proved to be a trisomy 18 and the third case a trisomy 21.