[The indications for the management of fetuses with choroid plexus cysts].

Choroid plexus cysts (CPC) in the fetus are still the subject of considerable debate in the literature. Because of their association with aneuploidy, and especially with trisomy 18, of which they are an ultrasonographic marker, the detection of fetal CPC now poses the problem of how these cases should be managed, since most occur in young women (there being no correlation between CPC and age), and since the incidence among the general population is fairly high (around 1%). With the aim of contributing further to the debate, a retrospective study was performed of all cases of fetal CPC diagnosed in our Centre between January 1984 and August 1994, together with a review of the relevant literature. There were 95 cases of fetal CPC with complete neonatal and necroptic data available. These cases included women recruited in the course of routine screening for congenital malformations carried out in our Centre at 14 and 21 weeks gestation, women referred to us from other Centres, and women recruited in the course of amniocentesis indicated for those aged over 35. In all cases in which fetal CPC was detected, a careful ultrasonographic examination was performed to exclude the presence of even the smallest morphologic anomaly. Whenever the fetus was found to have an anomaly karyotyping was done. If the CPC was not associated with any morphologic anomaly, karyotyping was proposed only to those women at risk of aneuploidy because of their age. There were 11 cases of trisomy 18, all of which presented morphologic anomalies associated with CPC. Some of these anomalies where "minor", however, and therefore difficult to assess even when a careful ultrasonographic examination was performed by an experienced operator (Intra ventricular septal defect, single umbilical artery). In 2 cases, CPC was associated with trisomy 21. Both women were aged over 35. All the other cases of CPC not associated with morphologic anomaly were normal on postnatal examination. From a meta-analysis of the literature, two distinct management protocols emerge for the problem of "isolated CPC detected at ultrasonographic examination". One group of authors recommends karyotyping for all women with fetal CPC, considering the presence of CPC in itself a risk factor for aneuploidy. The second group, to which we ourselves belong, believes it is sufficient to perform a careful ultrasonographic examination so as to exclude the presence of other morphologic anomalies associated with the CPC. Karyotyping should be proposed only to women at risk of aneuploidy because of their age (> 35). A review of the biggest series reported in the literature shows that, of a total of 1670 fetuses with CPC, 94 were trisomy 18. None of the cases of CPC "in isolation" emerged as being associated with this aneuploidy. However, numerous cases of trisomy 18 have been described in which CPC is associated with "minor" morphologic anomalies in the fetus which may be difficult to detect. It is therefore essential to perform a careful ultrasonographic examination in all cases of CPC, preferably in a Centre with specialist knowledge of ultrasonography. If this option is not available, then karyotyping of all women with fetal CPC is clearly advisable.