Rh-INCOMPATIBILITY

Hemolytic Disease of Newborn (ERYTHROBLASTOSIS FETALIS)

Dr. Muhammad Sajjad Sabir MBBS, DCH, MCPS, FCPSAssistant Prof. Paediatrics

Hemolytic disease of newbornThe term 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

Hemolytic disease of newbornIt is a condition in which the life span of the fetal/neonatal RBC is shortened due to maternal allo-antibodies against red cell antigens acquired from the fatherSORate of RBCs destruction is accelerated BUT ability of bone marrow to respond is NORMAL

It was a major cause of fetal loss and death among newborn babies

EtiologyRh incompatibility: Hemolytic disease occurs most frequently develops when an Rh ve mother conceives a fetus which is Rh +ve

ABO incompatibility: mother has blood type O and the fetus has blood type A or B or AB

Other causes: Other Minor blood group antigens(kell, kid )Thalassemia Autoimmune Hemolytic Anemia

The Rh factor , Rh+ and Rh- usually refers to presence or absence of antigen-D

There are two alleles of antigen: D and d

A person who is Rh -ve has two recessive traits, dd

Anyone who has at least one D (DD or Dd) is Rh+veRh-BLOOD GROUPING SYSTEM

Rh incompatibility:Rh incompatibility is a condition which develops when an Rh negative mother conceives a fetus which is Rh positive.

Isoimmunization:When the mother produces Abs directed against fetus RBC surface AgCause Feto- maternal BleedRisk Factors of Feto-maternal Bleed: AmniocentesisEctopic pregnancy

Fetal RBC Rh Antigen : Rh D Ag Mother produces: Anti Rh (D) Abs

PATHOGENISIS

DEFINITION:Rh incompatibility is a condition which develops when there is a difference in Rh blood type between that of the pregnant mother (Rh negative) and that of the fetus (Rh positive)

Rh Type and Pregnancy A person's Rh type is generally most relevant with respect to pregnancies

If the pregnant woman is Rh -ve and her husband Rh+ve, there is possibility of Rh incompatibility

If the pregnant woman and her husband are Rh negative, there is no reason to worry about Rh incompatibility

Usually placenta is barrier to fetal blood entering maternal circulation. Sometimes during pregnancy or birth, fetomaternal haemorrhage (FMH) can occur The womans immune system reacts by producing anti-D antibodies that cause sensitisation

Subsequent pregnancies antibodies can cross placenta and destroy fetal erythrocytes.

Conditions affecting 1st pregnancy :MiscarriageAbortionFeto-maternal haemorrage

The haemolytic disease of fetus and new born caused by Rh isoimmunisation can occur during the first pregnancy, but Usually sensitisation during the first pregnancy or birth leads to extensive destruction of fetal RBC during subsequent pregnancies

Pathogenesis

Fetomaternal Hemorrhage

Maternal Antibodies formed against fetus derived antigens

During subsequent pregnancy, placental passage of maternal IgG antibodies

Maternal antibody attaches to fetal red blood cells

Fetal red blood cell hemolysis

Pathogenesis; beforebirth

Pathogenesis; afterdelivery

Clinical Presentation

Hemolysis ed bilirubin levels

Rh incompatibility can cause symptoms ranging from very mild to fatal.

After delivery bilirubin is no longer cleared (via placenta) from the neonate's blood Jaundice (within 24 hours of life)

Possibility of acute or chronic Kernicterus

Sign &symptom

Mildest form- Rh incompatibility: 1-Hemolysis with the release of free hemoglobin into the infant's circulation

2- Jaundice

Prenatal manifestations : Hydrops fetalis / Erythroblastosis FetalisMassive fetal RBC destruction Profound anemiapallor high-output heart failure (CCF) Enlarged liver / spleenGeneralized Edema Ascites andRespiratory distress

Severe form- Rh incompatibility

Severe form- Rh incompatibility

1- severe forms petechiae and purpura

2- Severe anemiaFetal heart failure stillborn orDeath of infant shortly after delivery

2- Total body swelling

3- Respiratory distress (if infant has been delivered)

4- Circulatory collapse

5- Kernicterus. (bilirubin encephalopathy) (Neurological syndrome in extremely high levels of indirect bilirubin (>20 mg/dL).

6- It occurs several days after delivery and is characterized initially by... A) Loss of the Moro reflex. B)Poor Feeding. C) Decreased activity

LATER At last it may lead to death of the child immediately after its birth

Investigations

Blood groupingMother: Rh NegativeFather: Rh PositiveBaby: Rh PositiveDirect Coombs test: Positive in INFANTIndirect Coombs test: Positive in MOTHERBiochemical testHyperbilirubinemiaHypoalbuminemiaLDH: IncreaseHaptoglobin Decrease

Blood SmearPolychromasiaAnisocytosis Erythroblasts (nucleated RBCs) No Spherocytes

CBCTLC: normalHb: Hb MCV, MCH, HCHC : Normal or IncreasePlatelets: Normal to Decrease Reticulocytosis (6 to 40%)

Coombs testDirect Coombs test: diagnoses HDNThe direct Coombs test detects maternal anti-D antibodies that have already bound to fetal RBCs This is called the direct Coombs test because the anti-Ig binds "directly" to the maternal anti-D Ig that coats fetal RBCs in HDN

Finds anti-D antibodies in mother's serum. If these were to come into contact with fetal RBCs they would hemolyse them and hence cause HDN.

This is called the indirect Coombs test because the anti-Ig finds "indirect" evidence of harmful maternal antibodies, requiring the addition of fetal RBCs to show the capacity of maternal anti-D to bind to fetal RBCsIndirect Coombs test: used in the prevention of HDN

Management

If there is evidence of erythroblastosis

Notify Pediatrics team for possibilitye delivery of a compromised newborn

Management

ManagementBefore birth(Antenatal) options:Intrauterine RCC transfusion - blood transfused into fetalumbilical vein or

Early induction of labor when Pulmonary maturity has been attained, Fetal distress is present, or 35 to 37 weeks of gestation have passed

The mother may also undergo plasma exchange to reduce circulating levels of antibody by as much as 75%

After birth(Postnatal)Treatment depends on the severity of condition:Phototherapy Transfusion with compatible RCC, Exchange transfusion with a blood type compatible with both the infant and the motherSupportive care Temperature stabilization MonitoringSodium bicarbonate ( correction of acidosis)O2/ assisted ventilation

Management:Phototherapy for neonate with mild jaundice

Exchange transfusion in Severe cases

For Mother (Antenatal)Rh -ve mothers (pregnant with a Rh+ve infant are given) Rh immune globulin (RhIG) to prevent sensitization to D antigen RhoGAM protects against the effects of early transplacental hemorrhage (as recommended by the American College of Gynecologists). at 28 weeks during pregnancy at 34 weeks Plasma exchange to reduce circulating levels of antibody by as much as 75%

Close monitoring of fetal well-being, as reflected by Rh titers, amniocentesis results, and sonography

For Mother (Postenatal)Rh -ve mothers with Rh+ve infantInj RhoGAM must given within 72 hours of delivery of the newborn.

Preventing HDNDetermine Rh status of the motherIf the mother is not sensitized, reduce the risk of future sensitizationIf the mother is sensitized, determine whether the fetus is at risk and monitor accordinglyTo prevent Isoimmuization of yet unimmunized mother give Anti Rh D IgG (Rhogam) IntraMuscular at 28 weeks of gestation.

Summary:

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