[Fetal choroid plexus cysts: a real dilemma!].

The clinical significance of the fetal choroid plexus cysts, observed by prenatal sonographic examination, is now a days still discussed. A consequence of this situation is the discordance of opinions about the question of whether karyotype analysis is always necessary to evaluate chromosomal anomalies sometimes correlated, especially in the presence of (as some authors have reported) large (> 1 cm), bilateral, persistent cysts and of other structural abnormalities. We have effected a prospective study to estimate the incidence of fetal choroid plexus cysts and to establish the obstetrical behaviour to be adapted in these cases. During 834 routine ultrasonographic examinations at 18-21 weeks' gestational age, we have evaluated the presence of fetal choroid plexus cysts in 9 fetuses, with an incidence of 1.07%. Three of these cysts were larger than 1 cm, three were bilateral. Karyotype analysis, effected in all cases, diagnosed a case of Trisomy 18 in a fetus who ultrasonographically showed, in addition to a unilateral cyst of 1.2 cm, also a diaphragmatic hernia. Careful ultrasound follow-up revealed that all the cysts disappeared spontaneously, but two of them (whose dimensions were larger than 1 cm) were still visible at 24 weeks' gestation and probably this age will be too advanced to begin a chromosome analysis. In conclusion, we think that the presence of fetal choroid plexus cysts always imposes a careful ultrasonographic evaluation of fetal morphology and, since there is always the risk that other small fetal anomalies (evocative of abnormal fetal karyotypes) wight not be noted, we believe that it is better, in any case, to recommend to the patient a prenatal cytogenetical analysis.