[Morphological aspects of lethal chromosome errors]

Correlations have been established between phenotype and karyotype in spontaneously aborted specimens. The criteria used to determine the phenotype were based on estimated developmental age and macroscopic examination of embryo and placenta, taking into account the morphological modifications due to in utero retention. The probability that a chromosomal aberration was the cause of the abortion is high when the developmental arrest occurred before 5-6 weeks and the expulsion was delayed. The frequency could be estimated at 75% when the developmental arrest was at 2-3 weeks, and 65% when the developmental stage reached 5-6 weeks. Main anatomical features are described permitting an attempt to assign the type of chromosomal anomaly by ultrasonographic examination.