Hemolytic disease of newborn Dr. Tariq M.Roshan Dept. of Hematology PPSP

Objectives Definition & characteristics ABO vs Rh hemolytic disease of the newborn Pathogenesis Incidence Blood types of mother and baby Severity of disease Laboratory data Prevention Rh immune globulin Tests for feto-maternal hemorrhage Exchange transfusion protocol

Hemolytic disease of newborn Hemolytic disease of the new born and fetus (HDN) is a destruction of the red blood cells (RBCs) of the fetus and neonate by antibodies produced by the mother It is a condition in which the life span of the fetal/neonatal red cells is shortened due to maternal allo-antibodies against red cell antigens acquired from the father

Antibodies Five classes of antibodies IgM IgG IgA IgD IgE Blood groups specific antibodies are IgM and rarely

Biochemistry of antibodies Made from four polypeptide chains Two light (L) chains Two identical heavy (H) chains Each class has immunologically distinct heavy chain

Biochemistry of antibodies IgG1 IgG2 IgG3 IgA IgM IgE Compliment fixation ++ + +++ - Placental transfer Lymphocyte / macrophage FcR binding

Blood group antibodies Blood group antibodies can be classified as Naturally occurring and immune antibodies Depending on presensitization Cold and warm antibodies Thermal range of antibodies Most natural Abs are cold & some e.g wide thermal range like Anti A and Anti B Most immune Abs are warm and can destroy red cell in-vivo Complete and incomplete antibodies Depends on agglutination of saline suspended red cells IgM is complete antibody; most naturally occurring antibodies are complete and of IgM class IgG is incomplete antibody

Antibodies of ABO system Anti- A Naturally occurring Immune Anti- B Anti- A1 Anti- H

Antibodies of Rh system Naturally occurring Anti- E Occasionally anti-D and anti Cw Immune antibodies D antibodies are more immunogenic Other are anti c, E, e, C. Most common is anti- E After anti- D, anti- c is the common cause of HDN (The vast majority of Rh antibodies are IgG and do not fix complement)

Antibodies from other blood group systems Anti- K Kell blood group system Usually is immune antibody Warm Ab Anti- Jka Kidd blood group system

Complement Complements are series of proteins, present in plasma as an inactive precursors When activated and react sequentially with each other they mediate destruction of cells and bacteria Complement activation involves two stages Opsonization Lytic stage

Complement Antibodies can fix complement and cause rapid destruction of red cells Destruction depends on the amount of antibody and complement In ABO- incompatible transfusion no surviving A or B red cells can be seen after 1 hour of transfusion Why? Remember naturally occurring Abs. are IgM and fix complement mediating the hemolysis

Disease mechanism - HDN There is destruction of the RBCs of the fetus by antibodies produced by mother If the fetal red cells contains the corresponding antigen, then binding of antibody will occur to red cells Coated RBCs are removed by mononuclear phagocytic system

Neonatal liver is immature and unable to handle bilirubin Unconjugated bilirubin Conjugated bilirubin Coated red blood cell are hemolysed in spleen

Pathogenesis; before birth

Pathogenesis; after delivery

Clinical features Less severe form Severe forms Intrauterine death Mild anemia Severe forms Icterus gravis neonatorum (Kernicterus) Intrauterine death Hydrops fetalis Oedematous, ascites, bulky swollen & friable placenta Pathophysiology Extravascular hemolysis with extramedullary erythropoiesis Hepatic and cardiac failure

Hemolytic disease of newborn HDN BOFORE BIRTH Anemia (destruction of red cells) Heart failure Fetal death AFTER BIRTH Build up of bilirubin Kernicterus Severe growth retardation

P N Blood film of a fetus affected by HDN showing polychromasia and increased number of normaoblasts

Rh HEMOLYTIC DISEASE OF NEWBORN Antibodies against Anti-D and less commonly anti-c, anti-E Mother is the case of anti-D is Rh -ve (negative) Firstborn infant is usually unaffected Sensitization of mother occurs During gestation At the time of birth All subsequent offspring inheriting D-antigen will be affected in case of anti-D HDN

Fetomaternal Hemorrhage Pathogenesis Fetomaternal Hemorrhage Maternal Antibodies formed against Paternally derived antigens During subsequent pregnancy, placental passage of maternal IgG antibodies Maternal antibody attaches to fetal red blood cells Fetal red blood cell hemolysis

Factors affecting immunization and severity Antigenic exposure Host factors Antibody specificity Influence of ABO group ABO-incompatible Rh- positive cells will be hemolysed before Rh antigen can be recognized by the mother’s immune system

Diagnosis and Management Cooperation between Pregnant patient Obstetrician Her spouse Clinical laboratory

Recommended obstetric practice History; including H/O previous pregnancies or and disease needing blood transfusion ABO and Rh testing Antibody detection; To detect clinically significant IgG Ab which reacts at 370C Repeat testing required at 24 or 28 weeks if first test negative Antibody specificity Parental phenotype Amniocyte testing

Amniocentesis and cordocentesis Antibody titres Difference of 2 dilutions or score more than 10 is significant Amniocentesis and cordocentesis Concentration of bilirubin Spectrophotometric scan Indirect method Increasing or un-change OD as pregnancy advance shows worsening of the fetal hemolytic disease Fetal blood sample can be taken and tested for Hb, HCT, blood type and DCT (Direct Coombs test) Percutaneous Umbilical blood sampling

Liley graph

Diagnosis and Management contd. Intrauterine transfusion Zone II or III Cordocentesis blood sample Hb less than 10g/dl Ultrasound evidence of hydrops Early delivery Phototherapy Newborn transfusion Exchange transfusion Effects of transfusion Removal of bilirubin Removal of sensitized RBCs, and antibodies Suppression of incompatible erythropoiesis

Diagnosis and Management contd. Selection of blood Group O RBCs Rh-negativve units for Rh-negative case Whole blood group O Blood less than 7 days old

Diagnosis and Management contd.

Prevention of Rh- HDN Prevention of active immunization Administration of corresponding RBC antibody (e.g anti-D) Use of high-titered Rh-Ig (Rhogam) Calculation of the dose Kleihauer test for fetal Hb

Mechanism of action Administered antibodies will bind the fetal Rh- positive cells Spleen captured these cells by Fc-receptors Suppressor T cell response is stimulated Spleen remove anti-D coated red cells prior to contact with antigen presenting cells “antigen deviation”

ABO HEMOLYTIC DISEASE OF NEW BORN For practical purpose, only group O individuals make high titres IgG Anti-A and anti-B are predominantly IgM ABO antibodies are present in the sera of all individuals whose RBCs lack the corresponding antigens

ABO HDN contd. Signs and symptoms Laboratory findings Treatment Two mechanism protects the fetus against anti-A and anti-B Relative weak A and B antigens o fetal red cells Widespread distribution of A & B antigen in fetal tissue diverting antibodies away from fetal RBCs Anemia is most of the time mild ABO- HDN may be seen in the first pregnancy Laboratory findings Differ from Rh- HDN; microspherocytes are characteristic of ABO- HDN Bilirubin peak is later; 1- 3 days after birth Collection of cord blood and testing eluates form red cells will reveal anti-A or anti-B Treatment Group O donor blood for exchange transfusion which is rarely required

HDN- due to other antibodies Anti-c Usually less severe than that cause by Anti-D Anti-K May cause severe fetal anemia Blood transfusion for the treatment should lack the appropriate antigen

Summary. Hemolytic disease of newborn occurs when IgG antibodies produced by the mother against the corresponding antigen which is absent in her, crosses the placenta and destroy the red blood cells of the fetus. Proper early management of Rh- HDN saves lives of a child and future pregnancies ABO- HDN is usually mild Other blood group antigens can also cause HDN