Immune hydrops (erythroblastosis fetalis, hemolytic disease of the newborn)
Hemolytic disease of the newborn is caused by specific
maternal antibodies directed against red cell antigens of the
fetus. These are largely Rh (D) antigens.
- Pre-requisite of Rh isoimmunization: Rh- mother and Rh+ fetus.
- The mother is sensitized to Rh antigen by Rh+ fetal erythrocytes that
reach the maternal circulation. The mother is thus stimulated to
production of anti-Rh antibodies. Maternal IgG antibodies cross
the placenta, attach to the red blood cells and lead to hemolytic
anemia in the fetus. Compensatory mechanisms used by the fetus
include extensive activation of the hematopoeitic tissue and increased
cardiac output. Congestive heart failure and generalized edema are
marks of decompensation. The sensitization occurs most often during
the first childbirth, so the second and any following pregnancy
are at risk of hemolytic disease. The immunization also develops
following invasive examination durign pregnancy and abortion but
the volume of transplacental bleed is lower than during childbirth.
There is a very effective preventive program of Rh-isoimmunization.
Intravenous drug abuse in young women has been reported as the most
common cause of Rh isoimmunization today.
Rare causes of erythroblastosis fetalis:
Isoimmunisation against other antigens of the Rh system
(C, E) or antigens Kell, Lewis occurs rarely. The clinical
signs are the same as for the original anti-D disease.
Pre-requisite: Mother of group O and infant of group A or B.
Hemolytic disease of the newborn in cases of ABO
incompatiblity is usually mild. It presents as fetal anemia
in the third trimestr of pregnancy and moderate jaundice after
delivery. Hydrops fetalis is an exceptional complication.
- Clinical stages of the hemolytic disease of the newborn:
- anemia neonatorum
- icterus neonatorum
- hydrops fetus universalis: the most severe stage of
the hemolytic disease; a hydropic fetus is stillborn
or dies soon after birth
- Prevention: Administration of the anti-Rh (D)
immunoglobulin to Rh- women with Rh+ newborn within 72
hours of delivery, also to Rh- women following 2nd trimestr
abortion, chorionic villi sampling, amniocentesis and cordocentesis
- generalized tissue edema
- the placenta is enlarged, pale and very friable
Increased extramedullary hematopoiesis. Hepatic sinusoids are
crowded by immature nuclated red cells precursors.
Placenta: Villous immaturity, abundance of Hofbauer cells, persistent
cytotrophoblastic layer, deacreased vascularity, nucleated red blood
cells within the vessels.
Spleen with extramedullar hemopoiesis (72722)