OBJECTIVE: To track and analyze two false positive cases from non-invasive 
prenatal testing for potential fetal aneuploidy.
METHODS: The two cases, respectively reported to have XO (+++) and T18 (1/20) 
XO(+), were analyzed with conventional karyotyping, fluorescence in situ 
hybridization (FISH) and massively parallel genomic sequencing (MPS).
RESULTS: The first fetus, who was suspected for XO(+++), was verified to have 
super female syndrome (47,XXX/46,XX) due to confined placental mosaicism by 
karyotyping of amniotic fluid cells, FISH analysis of placenta and massively 
parallel sequencing (MPS) of fetal tissue. The second fetus, suspected to have 
trisomy 18 (1/20) XO(+), was verified to have Turner syndrome by karyotyping, 
FISH and MPS analyses of umbilical cord blood cells. And the karyotype was 
45,X[48]/46, X, der(X) del(X) (p11.21) del(X) (q13.3)[62].
CONCLUSION: Non-invasive prenatal testing carries a risk for false positive 
diagnosis of fetal sex chromosome and trisomy 18. Combined cytogenetic and 
molecular techniques are required to ensure an accurate diagnosis.