The pathophysiology of Hydrops fetalis

Abstract

Hydrops fetalis (HF) is a condition that develops during foetal life. It is defined as the abnormal accumulation of fluid in at least two serous cavities and/or within the soft tissues of the foetus. This includes ascites, pericardial effusion, skin oedema and pleural effusion (1,2). Studies have shown that the current incidence of HF is 1.80 per 1,000 total births with a mortality rate as high as 50% to this day, despite the advancements made in foetal intervention and neonatal care (3-5). There are two main causes of HF, immune and non-immune. The immune cause of HF was previously the major cause of HF, however, due to the introduction of preventative medicine, there has been a marked reduction of cases in the western world, which have now been surpassed by the non-immune causes (6),(7,8). Immune causes are due to antigen-antibody incompatibility of the mother and the developing foetus, leading to maternal immunological response to the paternally inherited antigens of the foetus (9). Non-immune causes include cardiovascular disorders, lymphatic dysplasias, haematological abnormalities, chromosomal imbalances, infections, conditions during pregnancy, metabolic disorders, tumours, and idiopathic ones. The pathophysiology leading to non-immune hydrops fetalis (NIHF) hence, depends on the cause.