Edema Hydrops fetalis HP:0005099 SNOMEDCT_US:276508000 UMLS:C0020305 The most common causes of hydrops fetalis are hematologic (including isoimmunization because of Rhesus incompatibility and other causes), hereditary hemolytic disorders, fetal hemorrhage, disorders of red cell production), cardiovascular disorders, infections, certain intrathoracic malformations, and idiopathic forms. The abnormal accumulation of fluid in two or more fetal compartments, including ascites, pleural effusion, pericardial effusion, and skin edema. HP:0001789 Fetal anomaly