Hydrops fetalis due to haemolytic disease

**Definition:** A fetal condition characterised by an accumulation of fluid or oedema in at least two fetal compartments, including subcutaneous compartments, the pleura, the pericardium, or the abdomen, due to the antibody-mediated break-down of fetal red blood cells.

**Exclusions:** - Hydrops fetalis not due to haemolytic disease