Rh-INCOMPATIBILITY

BYDr.GOWTHAM.B

Synopsis:Rh factorRh blood group systemRh typingRh incompatibilitySymptomsDetectionTreatmentPrevention of rh incompatibility

Rh-Factor

• The Rhesus factor gets its name from experiments conducted in 1937 by

scientists Karl Landsteiner and Alexander S. Weiner.

• Their experiments involved rabbits which, when injected with the Rhesus monkey's red blood cells, produced an antigen that is present in the red blood

cells of many humans.

•The genotype is determined by the inheritance of 3 pairs of closely linked allelic genes situated on chromosome 9 named as

D/d, C/c, E/e ……….. (Fisher- Race theory)

Rh-BLOOD GROUPING SYSTEM

• First demonstrated in rhesus monkey

• Blood groups are classified as Rh positive and Rh negative

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

•There are two alleles, or genetic variants , of this antigen: D and d.

•A person who is Rh- has two recessive traits, dd. Anyone who has at least one D-DD or Dd-is Rh+

Rh Type and Pregnancy

• A person's Rh type is generally most relevant with respect to pregnancies

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

•If she is Rh negative and her husband is Rh positive,the baby will inherit the father's blood type ,creating incompatibility between mother and her fetus.

•If some of the fetal blood gets into mother's blood stream, her body will produce antibodies.

•These antibodies could pass back through the placenta and harm the developing baby's red blood cells, causing very mild to very serious anemia in the fetus.

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)

• Usually placenta acts as barrier to fetal blood entering maternal circulation.However,sometimes during pregnancy or birth,fetomaternal haemorrhage (FMH) can occur. The woman’s immune system reacts by producing anti-D antibodies that cause sensitisation

•In subsequent pregnancies antibodies can cross placenta and destroy fetal erythrocytes. 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

Conditions which affects 1st pregnancy are:

MiscarriageAbortionFeto-maternal haemorrage

Sign &symptom of Rh incompatibility: • Rh incompatibility can cause symptoms

ranging from very mild to fatal.

• Mildest form- Rh incompatibility: 1-Hemolysis (Destruction of the red blood cells)

with the release of free hemoglobin into the infant's circulation.

2- Jaundice (Hemoglobin is converted into,bilirubin which causes an infant to become yellow.

Fetal hemolysis

jaundice

Severe form- Rh incompatibility

1- Hydrops fetalis (Massive fetal red blood cell destruction).

2- It causes Severe anemiaFetal heart failure Death of the infant shortly after delivery.

2- Total body swelling.

3- Respiratory distress (if the infant has been delivered)

4- Circulatory collapse.

5- Kernicterus. (Neurological syndrome in extremely jaundiced infants)

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

1-There are no any physical symptoms can be seen in rh incompatibility.

2-If the woman just found out she is pregnant,she should undergo blood-type test. This test determines her blood type and Rh factor.

3-Blood test that will determine whether she is Rh positive or Rh negative

DETECTION OF Rh INCOMPATIBILITY:

TREATMENT Antenatal:

-Intrauterine blood transfusion Intraperitoneal transfusion - blood transfused into fetal abdomen.

-Intravascular transfusion - blood transfused into fetal umbilical vein. 

•Postnatal:

-Phototherapy for neonatal jaundice in mild disease

-Exchange transfusion if the neonate has moderate or severe disease (the blood for transfusion must be less than a week old, Rh negative, ABO compatible with both the fetus and the mother, and be cross matched against the mothers serum)

Phototherapy ofneonatal jaundice:

-By using special immune globulins, called “-RhoGAM“ at 28 weeks of pregnancy.

- If the baby is born Rh positive, another dose is administered within 72 hours after delivery. This will prevent her body from creating any future antibodies that could cause harm during a pregnancy.

PREVENTION:

TRANSFUSION INCOMPATIBILITY

Wrong transfusion can cause agglutination of blood in the recipient Hence before transfusion of blood, along with identification of ABO blood group, it is necessary to test compatibility of Rh factor.

Summary: