Finding of fetal chromosomal mosaicism complicates genetic counseling, as
well as pregnancy management. The aim of this study was to determine the risk
of confined placental mosaicism in short term culture of chorionic villous
samples. We conducted a retrospective review of karyotype analysis results
obtained after chorionic villous sampling (CVS) in two years period. A 420
samples of chorionic villi were taken transabdominally and obtained by a
semidirect method (overnight incubating culture). All fetuses with CVS
mosaicism were under the intensive perinatal care. In all cases of chromosome
mosaicism the additional karyotyping was performed from fetal blood samples
after 22nd gestational week in order to exclude true fetal mosaicism. After
delivery newborns were examined by experienced pediatrician. From 420
analyzed samples in 11 (2,6%) cases we found placental mosaicism. No
anomalies were seen in genetic sonogram of this fetuses and mosaicism was
confirmed only in one case. Confined placental mosaicism (CPM) was found in
2,1% (9/420) of all analyzed cases, and it made 90% of all placental
mosaicism. In 60% (6/10) of placental mosaicism cases we found mosaicism with
single aberrant cell. Trisomy 21 mosaicism was the most frequent aberration
found in 30% of cases. Finding of mosaicism in chorionic villi sample is at
special importance for genetic counseling, because every case has to be
reveled individually regarding the type and level of mosaicism. Anyway, in
every case of placental mosaicism intensive antenatal monitoring is
necessary, with additional chromosome analysis from different tissue in
consideration of previous findings.
VP28.07: Impact of confined placental mosaicism on outcome of pregnancy
