Hydrops fetalis.

Congenital hydrops fetalis describes an abnormal accumulation of fluid in two or more compartments in a fetus. The disease is categorized based on the aetiology: immune- and non-immune hydrops fetalis. Today, the non-immune form is the most common. Once born, the child is initially handled symptomatically and will often need intensive care and treatment. Even though approximately one in five cases is still idiopathic, genetic diagnostic tools have become increasingly important in the diagnostic process. The prognosis depends on the aetiology and the gestational age when diagnosed and at birth, as argued in this review.