ABSTRACT
Hydrops fetalis refers to the presence of two or more of the following abnormal fetal fluid collections: ascites; pleural effusion; pericardial effusion; skin oedema; and polyhydramnios. The condition is subdivided into immune and non-immune hydrops. Immune hydrops is caused by red cell antibodies (red cell alloimmunisation). Non-immune hydrops fetalis comprises the subgroup of cases not caused by red cell alloimmunisation. The best-studied immunological cause of hydrops fetalis is pregnancy with rhesus positive fetus in a rhesus negative mother who is already sensitised by either a previous pregnancy or blood transfusion. The most commonly accounted cardiac lesions associated with hydrops are atrioventricular septal defect, hypoplastic left and right heart, an isolated ventricular or atrial septal defects. Parvovirus B19 is the most common infection associated with hydrops. The most common disorder described is recurrent fetal hydrops in mucopolysaccharidosis type VII, in which there is a deficiency of the enzyme beta glucuronidase.
