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Erythroblastosis fetalis
OVERVIEW: Hemolytic anemia of the fetus or newborn caused by transplacental transmission of maternal antibody. When severe, the anemia can result in extramedullary hematopoiesis, secondary organ dysfunction, heart failure, hydrops, and death. The name erythroblastosis refers to the presence of immature erythrocytes in the peripheral blood from accelerated hematopoiesis.
System(s) affected: Hemic/Lymphatic/Immunologic, Cardiovascular, Nervous
Genetics: Can occur when the fetus inherits a paternal blood group antigen lacking in the mother. The Rh D antigen is most frequently implicated. (For more on inheritance of Rh antigens, see Rh incompatibility.)
Incidence/Prevalence in USA:
• Uncommon
• About 9% of pregnancies have an Rh-negative mother with an Rh-positive fetus
• With Rho(D) immune globulin prophylaxis, risk of sensitization is reduced to less than 1% of susceptible pregnancies
Predominant age: Fetus and newborn
Predominant sex: Male = Female
SIGNS AND SYMPTOMS: • Pallor
• Respiratory distress
• Hepatomegaly
• Splenomegaly
• Ascites
• Hypotension/shock
• Edema/anasarca/hydrops
• Jaundice of newborn
• Purpura/bleeding problems
• Fetal death in utero
CAUSES: • Maternal isoimmunization to Rh antigen by transfusion of Rh-positive blood
• Maternal isoimmunization from exposure to fetal Rh antigens in prior pregnancy or current pregnancy
• Maternal isoimmunization to other blood group antigens (Kell, Duffy, Kidd, M, S, Diego, etc.) is unusual but may cause serious disease
RISK FACTORS: • Prior transfusion with incompatible blood
• Any Rh-positive pregnancy in Rh-negative woman
• Without prophylactic immunotherapy (Rh immune globulin), risk of Rh sensitization is up to 16% during or after term pregnancy, about 3% for spontaneous abortion and 5-6% for surgical abortion
• Sensitization by exposure to fetal blood can occur also with ectopic pregnancy, amniocentesis, chorionic villus sampling, placental trauma or manipulation, placental abruption
• Prophylaxis with Rh immune globulin greatly reduces but does not eliminate the risk
DIAGNOSIS DIFFERENTIAL DIAGNOSIS: • Fetal blood loss anemia
• Twin-to-twin transfusion
• Arteriovenous or cardiac malformations
• Hereditary hemolytic anemias
• Drug-induced hemolytic anemia
• Nonimmune fetal hydrops
• Hemolysis from intrauterine infection (syphilis, toxoplasmosis, CMV, others)
LABORATORY: • Positive indirect Coombs test (antibody screen) during pregnancy
• Positive direct Coombs test in fetus or newborn
• Anemia in fetus or newborn
• Reticulocytosis
• Nucleated RBC's on differential count
• Hyperbilirubinemia (indirect bilirubin)
• Thrombocytopenia
Drugs that may alter lab results: Prior administration of Rho(D) immune globulin may lead to weakly (false) positive indirect Coombs test in mother and direct Coombs test in infant
Disorders that may alter lab results: N/A
PATHOLOGICAL FINDINGS: • Erythroid hyperplasia of bone marrow
• Extramedullary hematopoiesis
• Hepatomegaly
• Splenomegaly
• Cardiac enlargement
• Pulmonary hemorrhages
• Enlargement, edema of placenta
SPECIAL TESTS: • Elevated amniotic fluid bilirubin (delta OD 450)
• Paternal blood typing may exclude pregnancy from being at risk
IMAGING: • Ultrasonography can demonstrate hepatomegaly, abdominal enlargement, ascites, or signs of hydrops
• Doppler flow studies of fetus are experimental in assessing degree of anemia
• Fetus may be severely affected without hydrops; ultrasound poor at predicting need for intervention
DIAGNOSTIC PROCEDURES: • Amniocentesis
• Umbilical cord blood sampling
TREATMENT APPROPRIATE HEALTH CARE: • Affected pregnancies usually managed at the tertiary care level because of the specialized, somewhat hazardous treatment measures involved
• Delivery should occur in an institution capable of performing exchange transfusion even if only mild involvement of infant is expected
• Infants with moderate or severe disease require neonatal intensive care
GENERAL MEASURES: • See Patient Monitoring
• Depending on severity of involvement, treatment of infant may include:
• Phototherapy
• Transfusion after delivery
• Exchange transfusion
• Diuretics and digoxin for hydrops
• Early delivery
• Intrauterine transfusion. Intravascular approach via the umbilical vein is becoming preferred over the intraperitoneal approach and appears to be more effective.
SURGICAL MEASURES: N/A
ACTIVITY: N/A
DIET: N/A
PATIENT EDUCATION: Griffith: Instructions for Patients, 5th Ed. Philadelphia, W.B. Saunders Co., to photocopy for patient
MEDICATIONS DRUG(S) OF CHOICE: N/A
Contraindications: N/A
Precautions: N/A
Significant possible interactions: N/A
ALTERNATIVE DRUGS: • Diuretics, inotropic agents, etc., may be used in addition to transfusion to manage heart failure in the newborn
• Promethazine, immune serum globulin, corticosteroids, and plasmapheresis have been tried as alternatives to invasive treatments but have not been effective
FOLLOW UP PATIENT MONITORING: • Antibody titer measured every few weeks during pregnancy. A titer of 1:16 or greater indicates need for further testing.
• Periodic amniocentesis for photometric determination of amniotic fluid bilirubin levels in pregnancies with elevated antibody titers. Results estimate the extent of fetal hemolysis and the need for cord blood sampling.
• Percutaneous umbilical blood sampling (PUBS, cordocentesis) for fetal blood type, hematocrit, reticulocyte count, presence of erythroblasts
• Fetal heart rate testing/ultrasonography to assess fetal status
• Amniocentesis for fetal lung maturity
PREVENTION/AVOIDANCE: • Rho(D) Immune Globulin (RhIG, RhoGAM, Gamulin Rh) given prophylactically to unsensitized, Rh-negative pregnant women at risk. Usually at 28-32 weeks gestation and at birth if infant is Rh positive (see Rh incompatibility topic).
• Artificial insemination with sperm from antigen-negative donor for isoimmunized woman married to antigen-positive man
POSSIBLE COMPLICATIONS: • Fetal distress requiring emergent delivery
• Fetal death in utero
• Disseminated intravascular coagulation (DIC)
• Pregnancy loss from umbilical blood sampling
• Pregnancy loss from intrauterine transfusion
• Asphyxia
• Neonatal hemolytic anemia, mild to severe
• Neonatal anemia from hematopoietic suppression after intrauterine transfusion
• Pulmonary edema
• Congestive heart failure
• Shock
• Neonatal jaundice, mild to severe
• Kernicterus
EXPECTED COURSE AND PROGNOSIS: • 50% of affected infants have mild disease and require no treatment (or treatment of anemia and jaundice only after delivery), and can be delivered at or near term
• 30% have moderate disease with anemia and hepatomegaly. They require close followup of the pregnancy for signs of deterioration which may require early delivery after 32-34 weeks or intrauterine transfusion prior to that age. After delivery exchange transfusion is likely to treat anemia and
hyperbilirubinemia.
• 20% have fetal hydrops, require intrauterine transfusion and delivery as early as 32-34 weeks
• Disease severity tends to worsen in successive affected pregnancies
• Hydrops is associated with poorer prognosis
• Without treatment overall perinatal mortality is 30%
• With appropriate monitoring and treatment most infants do well, even those requiring intrauterine transfusion
• Fortunately, with universal screening for Rh sensitization and widespread use of Rh immune globulin in 3rd trimester and/or birth have made disease relatively rare
MISCELLANEOUS ASSOCIATED CONDITIONS: N/A
AGE-RELATED FACTORS:
Pediatric: Exclusively affects fetus and neonate
Geriatric: N/A
Others: N/A
PREGNANCY: N/A
SYNONYMS: • Erythroblastosis neonatorum
• Hemolytic disease of the newborn
• Congenital anemia of the newborn
• Immune hydrops fetalis
• Icterus gravis neonatorum
ICD-9-CM: 773.0 Rh hemolytic disease in fetus or newborn
773.1 ABO hemolytic disease in fetus or newborn
773.2 Other hemolytic disease in fetus or newborn
773.3 Isoimmune hydrops fetalis
773.4 Isoimmune kernicterus
773.5 Isoimmune late anemia
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