Placental abnormalities detected by ultrasonography in a case of confined placental mosaicism for trisomy 2 with severe fetal growth restriction

Clinical outcome of confined placental mosaicism (CPM) is varied, from normal pregnancy to intrauterine fetal death. It has been suggested that CPM for trisomy 2 is less likely to cause serious adverse effect on pregnancy. We hereby report a case of CPM for trisomy 2, which presented severe fetal growth restriction (FGR) and placental abnormalities. A 30-year-old woman was referred to our hospital at 17(+2) weeks because of marked FGR. Ultrasonography demonstrated prominent placental hypertrophy with multiple focal defects without any fetal structural abnormalities. Amniocentesis at 18(+3) weeks revealed normal karyotype. Fetal growth rate worsened with gestational weeks, reaching -7 standard deviation at 36 weeks. At 37 weeks, the fetal condition suddenly deteriorated, ending in a stillbirth of a 756-g female baby. Postnatal cytogenetic analysis by array comparative genomic hybridization revealed trisomy 2 of the chorionic villi, and CPM for trisomy 2 was suggested as the cause of FGR and placental abnormalities.