Fetal loss in the first trimester after demonstration of cardiac activity: relation of cytogenetic and ultrasound findings

A retrospective comparison of cytogenetic and ultrasound findingsin first trimester spontaneous fetal loss after demonstrationof cardiac activity was made. The crownrump length (CRL) wasmeasured twice for each fetus resulting in spontaneous abortion:(i) CRL was measured in the viable state while demonstratingcardiac activity, and the growth deviation was expressed asthe measured/ expected CRL ratio (M/E CRL ratio); (ii) in thesame fetus, CRL was measured after confirmation of fetal death,and designated as the post-mortem CRL. The chorionic tissuesof these abortuses were karyotyped. The CRL of fetuses whichresulted in normal deliveries were also measured as controls.As a result, 16 of 24 abortuses displayed an abnormal chromosomalanalysis (67%). Themean M/E CRL ratio of still-viable fetuseswas smaller than that of control fetuses (0.74 ± 0.20versus 0.98 ± 0.13 respectively, P < 0.01). The differencesin ratio between karyotypically normal and abnormal abortuseswere not statistically significant. The post-mortem CRL of deadfetuses was >20 mm in four of five monosomy X, two of three21-trisomy, one of three triploidy and none of eight embryoswith normal karyotype and five other trisomies. In conclusion,our study demonstrated that the M/E CRL ratio could be usedas a predictor of spontaneous abortions, although it does notdiscriminate abnormal karyotypes from normal ones. The embryoswith a post-mortem CRL more than 20 mm have a higher likelihoodof suffering monosomy X or 21-trisomy. The ultrasonographicfindings might offer a cytogenetic clue as to a possible causeto the developmental arrest.