RESUMEN
BACKGROUND: An increased frequency of major limb malformations, especially terminal transverse limb defects, have been described in several studies of birth defects in children who had been exposed to the prenatal diagnosis procedure known as chorionic villus sampling (CVS). Vascular disruption has been proposed as the mechanism behind the fetal effect. We postulate that this mechanism is more likely to affect one or two middle fingers, rather than all five fingers. A recent report of the frequency of defects in any or all fingers in an unexposed control population enabled us to assess whether CVS is associated with an increased frequency of defects involving one or two fingers, as well as terminal transverse limb defects. METHODS: The frequency of limb-reduction defects affecting one or more fingers or toes, including those with constriction rings and tissue loss, in published studies of 20,236 children who had been exposed to CVS was compared with the frequency in 161,252 newborn infants who had not been exposed to CVS. Children with recognized genetic disorders were excluded. RESULTS: Several aspects of the limb deficiencies were more common in the CVS-exposed infants than in unexposed controls. The former were more likely to have: 1) any type of limb deficiency involving one or more fingers (p < .001); 2) absence/ hypoplasia of two fingers (p < .001); and 3) absence/hypoplasia of all five fingers (p = .015). The absence of the distal portion of the third finger was a distinctive type of limb-reduction defect in CVS-exposed infants. CONCLUSIONS: The occurrence of deficiencies in one or two fingers, including those designated as "amniotic band deformities," are as common as terminal transverse limb defects in CVS-exposed infants, and both are much more common than in unexposed infants. The absence of the distal portion of the third finger, with tapering and stiff joints, appears to be a distinctive effect of exposure to CVS.