incidence of Rh disease has markedly declined. Rh disease can be prevented by administration of anti-D IgG (Rho(D) Immune Globulin) injections to RhD-negative mothers during pregnancy and/or within 72 hours of the delivery. However, a small percentage of pregnant mothers are still susceptible to Rh disease even after receiving anti-D IgG (Rho(D) Immune Globulin). Non-immune pathophysiology Severe anemia leads to hyperdynamic circulation, which means high-output cardiac failure causes the blood to circulate rapidly. The excessive pumping of blood causes the left side of the heart to fail leading to pulmonary edema. 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. Twin-twin transfusion syndrome (TTTS) in pregnancies in which twins share a single placenta (hydrops affects the recipient twin) Twin anemia-polycythemia sequence (TAPS) Twin reversed arterial perfusion sequence (TRAPS) Maternal hyperthyroidism Fetal cardiac defects and skeletal defects Noonan syndrome Mirror syndrome, in which fetal and placental hydrops develops in association with maternal preeclampsia, edema and hypertension Down syndrome Diagnosis Hydrops fetalis can be diagnosed and monitored by ultrasound scans. An official diagnosis is made by identifying excess serous fluid in at least one space (ascites, pleural effusion, of pericardial effusion) accompanied