Cardiovascular malformations in spontaneously aborted human fetuses.

Among 57 spontaneously aborted fetuses with a crown-rump length (CRL) ranging from 30 to 180 mm, 5 were found to have cardiovascular malformations. The number of cases with cardiovascular malformations (numerator) and the number of observed fetuses (denominator) classified according to their CRL were as follows: CRL 30-49 mm, 1/9 (persistent left superior vena cava); 50-69 mm, 4/11 (one case each of membranous VSD with aberrant right subclavian artery, high muscular VSD, pulmonary stenosis with muscular VSD and overriding aorta, right aortic arch with membranous VSD); 70-99 mm, 0/7; 100-139 mm, 0/16; 140-180 mm, 0/14. The above results clearly show a high prevalence of cardiovascular malformations in spontaneously aborted fetuses with a CRL of less than 70 mm. The practicability and potential value of microdissection of small fetuses are stressed.