During the first pregnancy, the<unk> - mother’s initial exposure to fetal<unk> + red blood cells (RBCs) is usually not sufficient to activate her<unk> -recognizing B cells. However, during delivery, the placenta separates from the uterine wall, causing umbilical cord blood to enter the maternal circulation, which results in the mother’s proliferation of IgM-secreting plasma B cells to eliminate the fetal<unk> + cells from her blood stream. IgM antibodies do not cross the placental barrier, which is why no effects to the fetus are seen in first pregnancies for<unk> -D mediated<unk> . However, in subsequent pregnancies with<unk> + fetuses, the IgG memory B cells mount an immune response when re-exposed, and these IgG anti-Rh(D) antibodies do cross the placenta and enter fetal circulation. These antibodies are directed against the<unk> esus <unk>  factor, a protein found on the surface of the fetal RBCs. The antibody-coated RBCs are destroyed by IgG antibodies binding and activating complement pathways. The resulting anemia has multiple sequelae: # The immature hematopoietic system of the fetus is taxed as the liver and spleen attempt to put immature RBCs into circulation (erythroblasts, thus the previous name for this<unk>  erythroblastosis fetalis). # As the liver and spleen enlarge under this unexpected demand for RBCs, a condition called portal hypertension develops, and this taxes the immature heart and circulatory system. # Liver enlargement and the prolonged need for RBC production results in decreased ability to make other proteins, such as albumin, and this decreases the plasma colloid oncotic pressure leading to leakage of fluid into tissues and body cavities, termed hydrops fetalis. # The severe anemia taxes the heart to compensate by increasing output in an effort to deliver oxygen to the tissues and results in a condition called high output cardiac failure. # If left untreated, the end result may be fetal death. The destruction of RBCs leads to elevated bilirubin levels (hyperbilirubinemia) as a byproduct. This is not generally a problem during pregnancy, as the maternal circulation can compensate. However, once the infant is delivered, the immature system is not able to handle this amount of bilirubin alone and jaundice or kernicterus (bilirubin deposition in the brain) can develop which may lead to brain damage or death. Sensitizing events during pregnancy include c-section, miscarriage, therapeutic abortion, amniocentesis, ectopic pregnancy, abdominal trauma and external cephalic version. However, in many cases there was no apparent sensitizing event. Approximately 50% of<unk> -D positive infants with circulating anti-D are either unaffected or only mildly affected requiring no treatment at all and only monitoring. An additional 20% are severely affected and require transfusions while still in the uterus. This pattern is similar to other types of HDFN due to other commonly encountered antibodies (anti-c, anti-K, and Fy(a)).
Rh disease
Rh deficiency syndrome
3-M syndrome
Fanconi anemia
3C syndrome
Leukocyte adhesion deficiency-1
X linked thrombocytopenia
NEMO deficiency syndrome