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Fetal amniotic adhesions. Their topographic concordance with regionally clustered malformations
B R Davies1, J A Giménez-Scherer, J F Hernández-Sierra
1Departamento de Patología, Hospital General de México y Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Mexico City, Mexico.
Background:
The amniotic band disruption complex (ABDC) has been segregated recently into various phenotypes. In view of the pathogenic mechanisms that have been proposed, this study was designed to assess if it is one variable process or is composed of several distinct complexes.
Methods:
The 48 cases of fetuses with bands or placenta attached to fetal parts cited in this paper included nine new cases and 39 from the literature. They were organized first according to the embryonal topography of the malformations, then according to the position of the adhesions, and finally by the assessment of distances between the cases and between the malformations using the squared Euclidean distances for binary variables and cluster analysis.
Results:
In all three analyses, three groups were identified: 1) fetuses with cephalo-thoracic anomalies; 2) fetuses with caudal anomalies, and 3) fetuses with mixed anomalies. Nonetheless, overlap among the three groups was apparent. Thus, while fetuses with amniotic bands form three clusters, it appears that these are part of a spectrum and should be considered as variable manifestations of a single entity resulting from a single pathogenetic mechanism. An association was established between the localization of the adhesions and the malformations in various axes. Abdominoschisis, however, was not particularly related to adhesions at one or the other end of the fetus; a short umbilical cord was an almost universal finding. Single umbilical artery (SUA) was especially related to caudal adhesions and malformations (p = 0.004 and 0.001), as well as abdominoschisis (p = 0.002) and agenesis of the abdominal organs (p = 0.008).
Conclusions:
The association between amniotic adhesions to the fetus and multiple malformations occurring predominantly in the same area suggest that the former are the cause of the latter. The association of abdominoschisis, as well as a short umbilical cord, with malformations and adhesions in all areas, suggests that these are secondary phenomena to generalized embryonal and fetal tension. SUA, however, with a specifically regional association, is more likely to be due to disruption from exposure in cases with abdominoschisis, often accompanying the loss of abdominal organs.