Hydrops foetalis or hydrops fetalis is a condition in the fetus characterized by an accumulation of fluid, or edema, in at least two fetal compartments. By comparison, hydrops allantois or hydrops amnion is an accumulation of excessive fluid in the allantoic or amniotic space, respectively. Signs and symptoms
Locations can include the subcutaneous tissue on the scalp, the pleura (pleural effusion), the pericardium (pericardial effusion) and the abdomen (ascites). Edema is usually seen in the fetal subcutaneous tissue, sometimes leading to spontaneous abortion. It is a prenatal form of heart failure, in which the heart is unable to satisfy demand (in most cases abnormally high) for blood flow. Causes
Hydrops fetalis usually stems from fetal anemia, when the heart needs to pump a much greater volume of blood to deliver the same amount of oxygen. This anemia can have either an immune or non-immune cause. Non-immune hydrops can also be unrelated to anemia, for example if a fetal tumor or congenital cystic adenomatoid malformation increases the demand for blood flow. The increased demand for cardiac output leads to heart failure, and corresponding edema. Immune pathophysiology
Erythroblastosis fetalis, also known as Rh disease, is the only immune cause of hydrops fetalis. Rh disease is a hemolytic disease of newborns. Pregnant mothers do not always have the same blood type as their child. During birth or throughout the pregnancy, the mother may be exposed to the infants blood.
The build up of fluid in the lungs increases the pressure in the lungs leading to vasoconstriction. The coupled vasoconstriction and pulmonary hypertension causes the right side of the heart to fail which in turn, increases the venous hydrostatic pressure in the body. The summation of these effects ultimately leads to peripheral edema and ascites. All in all, the left side failure of the heart will lead to pulmonary edema whereas right side failure will lead to peripheral edema and ascites. The non-immune form of hydrops fetalis has many causes including:
Iron deficiency anemia
Paroxysmal supraventricular tachycardia resulting in heart failure
Deficiency of the enzyme beta-glucuronidase. This enzyme deficiency is the cause of the lysosomal storage disease called mucopolysaccharidosis type VII. Congenital disorders of glycosylation
Parvovirus B19 (fifth disease) infection of the pregnant woman (most common cause)
Cytomegalovirus in mother
Congenital pulmonary airway malformation (formerly called congenital cystic adenomatoid malformation)
Maternal syphilis and maternal diabetes mellitus
Alpha-thalassemia can also cause hydrops fetalis when all four of the genetic loci for α globin are deleted or affected by mutation. This is termed Hb Barts (consists of y-4 tetramers). Uncommonly, Niemann-Pick disease Type C (NPC) and Gaucher disease type 2 can present with hydrops fetalis. Turner syndrome
Tumors, the most common type of fetal tumor being teratoma, particularly a sacrococcygeal teratoma.