OC059: Karyotyping of fetuses with isolated choroid plexus cyst or with associated minor marker is not justified in a low-risk population

Abstract

Choroids plexus cysts (CPC) are important for their association with fetal aneuploidy, particularly trisomy 18, which some authors described almost 20 years ago. In spite of numerous works through the years a clear-cut link between trisomy 18 and CPC has not been found. We analyzed 16 272 patients referred to our centre from January 1998 to December 2002. Only the patients with a first examination between 16 and 23 gestational weeks were included. Fetuses with a CPC were checked for either an amniocentesis (amnio) or a normal outcome at birth. From the group of CPC extracted, fetuses with associated anomalies were noted. From the group with associated anomaly a group with minor and a group with major was extracted. From the total, 366 had CPC, that is 2.9%, 311 had no other associated anomalies; either the karyotype or the postnatal pediatric examination was normal, 55 of the patients had associated anomalies, from this group 12 fetus with present major anomaly were extracted and in two cases the amnio revealed two cases of trisomy 18. The other 10 cases had normal karyotype. The 43 fetuses with CPC and minor finding had either a normal amniocentesis or pediatric examination at birth. In addiction, in the period of study we identified overall 6 fetuses with karyotypically proven trisomy 18. In the 4 fetuses with trisomy 18, the presence of major anomalies in absence of CPC, strongly suggests the performance of a karyotype. In the isolated CPC there is not evidence of aneuploidy. If the isolated CPC had been aggressively pursued the total fetal loss would have been increased to 1.55 fetus assuming a commonly quoted risk of 1 : 200 miscarriage. Another reason is that the trisomy 18 is considered uniformly fatal, there is another important factor to consider the exposure of healthy population at the karyotype risk for recognized a very small population with a very poor prognosis.