Rh incompatibility


:dart:The Rh antigenic determinants are genetically transmitted from each parent, determine the Rh type, and direct the production of a number of blood group factors (C, c, D, d, E, and e). :ok_hand:

:speaking_head: Pathogenesis​:speaking_head:

:dart:Isoimmune hemolytic disease from Anti D is approximately 3 times more frequent among white persons than among black persons. :busts_in_silhouette:
:dart:When Rh(+)blood is infused into an Rh(-)woman through error, or when small quantities (usually >1 mL) of Rh(+) fetal blood containing D Ag inherited from an Rh(+) father enter the maternal circulation during pregnancy, with spontaneous or induced abortion, or at delivery, Ab formation against Ag may be induced in the unsensitized Rh-negative recipient mother. :pregnant_woman:
:dart:Once sensitization occur considerably smaller doses of Ag can stimulate an increase in Ab titer. :chart_with_upwards_trend:
:dart:Initially, a rise Ig M antibody occurs, which is later replaced by IgG antibody; the latter readily crosses the placenta to cause hemolytic manifestations.:fire::fire:
:dart:Hemolytic disease rarely occurs during a first pregnancy because transfusion of Rh(+) fetal blood into an Rh(-) mother occurs near the time of delivery, too late for the mother to become sensitized and transmit antibody to her infant before delivery. :pregnant_woman::pregnant_woman:

:speaking_head:Clinical Manifestions​:speaking_head:

:dart:A wide spectrum of hemolytic disease occurs in affected infants born to sensitized mothers, depending on the nature of the individual immune response.:male_detective:
:dart: The severity of the disease may range from only laboratory evidence of mild hemolysis (15% of cases) to severe anemia with compensatory hyperplasia of erythropoietic tissue leading to massive enlargement of the liver and spleen. :woman_teacher:
:dart:When the compensatory capacity of the hematopoietic system is exceeded, profound anemia occurs and results in pallor, signs of cardiac decompensation (cardiomegaly, respiratory distress), massive anasarca, and circulatory collapse.:sleeping_bed:
:dart: This clinical picture of excessive abnormal fluid in 2 or more fetal
compartments (skin, pleura, pericardium, placenta, peritoneum, amniotic fluid), termed hydrops fetalis, frequently results in death in utero or shortly after birth. With the use of RhoGAM to prevent Rh sensitization, nonimmune (nonhemolytic) conditions have become frequent causes of hydrops :zombie::zombie:
:dart: The severity of hydrops is related to the level of anemia and the degree of reduction in serum albumin (oncotic pressure), which is partly a result of hepatic dysfunction.:bomb::bomb: Alternatively, heart failure may increase right heart pressure, with the subsequent development of edema and ascites.
:dart:Failure to initiate spontaneous effective ventilation because of pulmonary edema or bilateral pleural effusions results in birth asphyxia; after successful resuscitation, severe respiratory distress may develop. :x::x:
:dart:Petechiae, purpura, and thrombocytopenia may also be present in severe cases as a result of decreased platelet production or the presence of concurrent disseminated intravascular coagulation.:bangbang::bangbang:
:dart:Jaundice may be absent at birth because of placental clearance of lipid-soluble unconjugated bilirubin, but in severe cases, bilirubin pigments stain the amniotic fluid, cord, and vernix caseosa yellow.:radioactive::radioactive:
:dart: Jaundice is generally evident on the 1st day of life because the infant’s bilirubin-conjugating and excretory systems are unable to cope with the load resulting from massive hemolysis. :warning::warning:
:dart:The risk of development of kernicterus from hemolytic disease is greater than from comparable nonhemolytic hyperbilirubinemia , although the risk in an individual patient may be affected by other complications (hypoxia, acidosis). :radioactive:
:dart:Hypoglycemia occurs frequently in
infants with severe isoimmune hemolytic disease and may be related to hyperinsulinism and hypertrophy of the pancreatic islet cells in these infants.:interrobang:

⁦🗣️⁩Laboratory Data🗣️

:dart:Before treatment, the direct Coombs test usually positive and anemia is generally present. :microscope::memo:
:dart:The cord blood hemoglobin content varies and is usually proportional to the severity of the disease; with hydrops fetalis it may be as low as 3-4 g/dL. :chart_with_upwards_trend:
:dart:may be within the normal range because of compensatory bone marrow and extramedullary hematopoiesis. :male_detective:
:dart:The blood smear typically shows polychromasia and a marked increase in nucleated RBCs.:chart_with_upwards_trend::arrow_up:
:dart: The reticulocyte count is increased. The white blood cell count is usually normal but may be elevated; thrombocytopenia may develop in severe cases.:negative_squared_cross_mark::arrow_up:
:dart: Cord bilirubin is generally between 3 and 5 mg/dL.