A Pathologist's Approach to Nonimmune Hydrops

Fetal hydrops is an uncommon, but frequently-lethal, complication of pregnancy. Hydrops can result from any of diverse etiologies, although it has classically been divided into immune and nonimmune hydrops. While the etiology for many cases can be determined prenatally, pathologists are nearly always called on to identify the underlying cause for those cases that remain unexplained at the time of delivery or termination. This brief review will be confined to nonimmune hydrops, and the discussion will particularly focus on the role of the pathologist in evaluating this condition.