Nonimmunologic hydrops fetalis: an etiopathogenetic approach through the postmortem study of 59 patients

Aiming at increasing our understanding of the various causative factors of nonimmunologic hydrops fetalis (NIHF) and their pathogenetic mechanisms, we have reviewed 59 cases of this condition from a total number of 4,175 pediatric post-mortem studies performed at the Department of Pathology of the Hospital La Paz from 1967 to 1987. We found eight cases (13.5%) without clinical, biochemical, or post-mortem findings justifying the development of hydrops fetalis, seven cases (12%) associated with certain pathologic findings that by themselves do not explain the development of hydrops and, finally, 44 cases (74.5%) in whom pathological findings may explain the development of the condition. Notwithstanding the etiological diversity of this last group, in 31 of these cases (70%), some common pathogenetic features may be recognized, basically a failure of the right ventricle of the heart in the fetus or newborn, due to a primary heart condition, to intracardiac tumors, or to obstructive phenomena at the level of the right venous drainage. In our opinion, whenever NIHF is diagnosed or suspected, causes of right cardiovascular failure should be investigated, since about 50% of all cases seem to be due to this pathogenetic mechanism.