Postmortem chorionic villus sampling: correlation of cytogenetic and ultrasound findings.

We performed chorionic villus samplings (CVS) in 795 cases in the first trimester during a 13-month period. Of these 35 were found to have a blighted ovum or missed abortion prior to the procedure. Nineteen women consented to have CVS. Ultrasonographic and cytogenetic findings in these 19 pregnancies were correlated. Expected gestational age was determined by last menstrual period. Observed gestational age was determined by crown rump length (CRL) (12 pregnancies) or gestational sac (GS) (7 pregnancies without fetal pole). The differences in days between the estimated and observed gestational ages was determined for each pregnancy. In all 19 CVS samples cytogenetic diagnosis documented aneuploidy. Ten cases had chromosome abnormalities virtually always lethal in the embryonic period (group I). Nine pregnancies had defects with moderate potential for fetal viability (group II). Gestations with low viability potential (group I) had estimated minus observed gestational age discrepancies (23.4 +/- 8.3 days) significantly greater than gestations with moderate viability potential (group II) (8.9 +/- 4.3 days) (P less than .001). The absence of a fetal pole was more common in group I. CVS in pregnancies with missed abortion or blighted ovum is feasible and has a high likelihood of documenting aneuploidy. Furthermore, the more severe the anomaly the more likely there will be very early fetal demise or intrauterine growth retardation.