Correlation of Prenatal Sonographic Diagnosis and Morphologic Findings of Fetal Autopsy in Fetuses With Trisomy 21

Objectives The purpose of this study was to compare the prenatal sonographic and postmortem pathologic findings of fetuses with trisomy 21. Methods Among 22,150 fetal chromosome analyses, trisomy 21 was diagnosed in 207 fetuses between 1990 and 2004. Findings of second‐trimester sonography and fetal autopsy were compared by organ system, and their correlation was assigned to 1 of 3 categories. Results In total, 83.1% of the 184 fetuses that constituted the final study group had 1 or more abnormal structural findings at postabortion pathologic examination, whereas in 16.9% of the cases, fetal pathologic examination did not reveal any defects in fetal anatomy. Among major structural defects, the agreement between sonographic and autopsy findings was greater than 60% of all abnormalities of these systems: central nervous system (65.4%), heart (67.4%), fetal hydrops (100%), and cystic hygroma (93.3%), whereas the concordance rate was lower in these organ systems: abdominal abnormalities (46.2%), renal anomalies (50%), facial abnormalities (1.2%), and extremities (4.4%). The rate of additional major findings at autopsy was 34.2%. These mainly involved 3 organ systems: heart, head, and abdominal anomalies. Some sonographic findings (n = 16) were not verified at autopsy. The concordances between sonographic and autopsy findings regarding soft markers were considerably high in these markers: increased nuchal fold thickness (72%), short femur/humerus (75%), and pyelectasis (51.9%). Conclusions Examining the correlation between sonography and pathologic findings may indicate possible directions of further development in sonographic screening for trisomy 21. In addition to obstetricians, pediatricians, and geneticists, specialized perinatal pathologists have an important role in the multidisciplinary management of prenatally diagnosed fetal malformations.