Hemolytic Disease of the Fetus and Newborn (HDFN)

Hemolytic Disease of the Newborn (HDFN)

Destruction of fetal/neonate RBCs by maternal antibodies.

Rh Antigen D

Primary cause of HDFN in 95% of cases.

Rh Immune Globulin (RhIG)

Introduced in 1968 to reduce Rh HDFN incidence.

Immunoglobulin G (IgG)

Only antibody class crossing the placenta.

Rh HDFN

Occurs when Rh-negative mother has Rh-positive fetus.

Maternal Immunization

Mother produces anti-D after exposure to fetal RBCs.

ABO Incompatibility

20% of pregnancies; affects A/B infants of group O.

Isohemagglutinins

Maternal antibodies that can cross the placenta.

Bilirubin Peak

Occurs at 1 to 3 days after birth.

Phototherapy

Treatment for elevated bilirubin levels in newborns.

Fetomaternal Hemorrhage (FMH)

Maternal alloimmunization caused by fetal RBC exposure.

Transplacental Hemorrhage

Fetal RBCs enter maternal circulation during pregnancy.

Amniocentesis

Procedure increasing risk of fetomaternal hemorrhage.

Immunoglobulin Subclasses

IgG1 and IgG3 are more effective in hemolysis.

Anti-Kell Antibody

Most significant non-Rh antibody causing HDFN.

Major Incompatibility

Mother's ABO incompatibility decreases detectable FMH.

Erythroblastosis Fetalis

Release of immature RBCs due to fetal anemia.

Hydrops Fetalis

Severe anemia leading to cardiac failure and edema.

Unconjugated Bilirubin

Produced from hemoglobin breakdown; poorly processed by newborn liver.

Microspherocytes

Abnormal RBCs due to increased fragility.

DAT (Direct Antiglobulin Test)

Test for antibodies attached to fetal RBCs.

Exchange Transfusion

Rarely needed for severe HDFN cases.

Kernicterus

Rare brain damage from high bilirubin levels.

Hepatosplenomegaly

Enlarged liver and spleen due to extramedullary hematopoiesis.

Antigenic Sites

Number of fetal RBC antigens affects hemolysis rate.

Maternal Liver

Metabolizes unconjugated bilirubin during pregnancy.

Bilirubin

A yellow compound from hemoglobin breakdown.

Postnatal Jaundice

Yellowing of skin within 12-48 hours after birth.

Positive DAT

Direct Antiglobulin Test indicating RBC sensitization.

Elution Studies

Tests to identify antibodies in cord blood.

HDFN

Hemolytic Disease of the Fetus and Newborn.

RBC Alloimmunization

Immune response against foreign RBC antigens.

Antibody Detection Test

Identifies maternal antibodies during pregnancy.

RhIG

Rho(D) Immune Globulin to prevent Rh sensitization.

Antibody Identification

Determining specific antibodies present in serum.

Antibody Titration

Measures antibody concentration affecting fetal health.

MCA-PSV

Middle Cerebral Artery Peak Systolic Velocity measurement.

Fetal Anemia

Insufficient red blood cells in the fetus.

Paternal Genotype Testing

Determines father's D antigen status via DNA.

Cordocentesis

Sampling fetal blood from the umbilical cord.

Intrauterine Transfusion

Blood transfusion to fetus before birth.

Direct Antiglobulin Test (DAT)

Test for antibodies attached to RBCs.

ABO Grouping

Determining blood type based on ABO antigens.

RhD Typing

Identifying Rh factor presence in blood.

Fetal DNA Testing

Testing fetal DNA for blood group antigens.

∆OD 450 nm

Measurement predicting fetal hemolytic disease severity.

High Bilirubin Levels

Condition requiring exchange transfusion intervention.

Intravenous Immune Globulin (IVIG)

Reduces hemolysis by competing with maternal antibodies.

Rosette Test

Screens for fetal D+ cells in maternal blood.

Fetal D+ Cells

Red blood cells from fetus with D antigen.

Kleihauer-Betke Test

Quantifies fetal cells in maternal circulation.

Acid Elution

Removes adult hemoglobin from maternal cells.

Fetal Hemoglobin (HbF)

Less susceptible to acid than adult hemoglobin.

Maternal Cells

Cells from the mother in blood tests.

Volume of Fetal Hemorrhage

Calculated from fetal and maternal cell counts.

Dosage Calculation

RhIG dosage based on fetal bleed volume.

Blood Selection for Transfusion

Use O RBCs, antigen-negative for maternal antibodies.

CMV-negative Donors

Blood donors screened for cytomegalovirus.

Weak D Phenotype

Serologic reagents may misidentify RhD type.

Anti-D Antibodies

Produced by Rh-negative mothers against Rh-positive blood.

RhD Genetic Testing

Accurate RhD typing for weak D patients.

Safety Recommendations

Adjust RhIG dosage based on decimal points.

Regular-Dose RhIG

300 µg protects against 15 mL packed RBCs.

Postpartum RhIG Administration

Given within 72 hours after Rh-positive delivery.

Positive Rosette Test

Indicates significant FMH requiring more RhIG.

Negative Rosette Test

No fetal D+ cells detected in maternal blood.

Positive KB Test

Indicates presence of fetal cells in maternal blood.

Negative KB Test

No fetal cells detected in maternal blood.

RhIG Ineffectiveness

No benefit after active immunization occurs.

Transfusion Timing

Blood units less than 7 days old preferred.

Fetal Cell Counting

Count fetal cells to determine RhIG needs.