Rh INCOMPATIBILITY

• Proteins (antigens) occurring only on surface of RBC’s

• Rh + if proteins present• Rh – if proteins absent• A+, A-, B+, B-, AB+, AB-, O+, O-• Most important for pregnancy• Inheritance is Autosomal Dominant• 15% Caucasian population are Rh-

Rh FACTOR

INTRODUCTION

• During Pregnancy, the mother and the fetus have different Rh protein factors, this condition is called Rh incompatibility.

• Like our blood type, we inherit our Rh factor type from our parents. Most people are Rh-positive, but a small percentage of people are Rh-negative

• Rh factor doesn’t directly affect the health. • However, Rh factor becomes important during pregnancy.

• Rhesus disease is a condition where antibodies in a pregnant woman's blood destroy her baby's blood cells. It's also known as haemolytic disease of the fetus and newborn (HDFN).

• If the mother is Rh-negative and her baby is Rh-positive, during pregnancy (and especially during labor and delivery) some of the fetus's Rh-positive red blood cells may get into the mother's bloodstream.

• SENSITIZATION – The process in which mother’s body will try to fight them off by producing antibodies against them.

Rh DISEASE?

Potential sensitizing events for Rhesus Disease• Miscarriage• Termination of pregnancy• Antepartum haemorrhage• Invasive prenatal testing (amniocentesis, cordocentesis etc.)• Delivery• Ectopic pregnancy

PATHOPHYSIOLOGY

CAUSES

•Ectopic pregnancy•Partial molar pregnancy•Blighted ovum•Antepartum bleeding•External version•Platelet transfusion•Placenta previa

•Placental abruption•Abdominal/pelvic trauma•In utero fetal death•Any invasive obstetric procedure (eg, amniocentesis)•Lack of prenatal care•Postpartum (Rh+baby)•Spontaneous abortion

Rh incompatibility can cause symptoms ranging from very mild to deadly. In its mildest form, Rh incompatibility causes the destruction of red blood cells. There are no other effects.

After birth, the infant may have:•Yellowing of the skin and whites of the eyes (jaundice)•Low muscle tone (hypotonia)•Lethargy•Swelling or edema (hydrops fetalis)

SYMPTOMS

Signs of fetal anemia• Polyhydramnios• Enlarged fetal heart• Ascites and pericardial effusions• Hyperdynamic fetal circulation (MCA doppler)• Reduced fetal movements• Abnormal CTG with reduced variability

Diagnosis

• MCA doppler• Cell free DNA• Kleihauer test• Amniocentesis and liley graph• Direct coomb’s test

SCREENING TESTS

• ABO & Rh Ab at 1st prenatal visit• At 28 weeks• Postpartum Bleeding• Antepartum bleeding and before

giving any immune globulin• Neonatal bloods ABO, Rh

GOLD STANDARD TESTS

• Indirect Coombs:mix Rh(D)+ cells with maternal serumanti-Rh(D) Ab will adhereRBC’s then washed & suspended in

Coombs serumRBC’s coated with Ab will be agglutinated

• Direct Coombs:mix infant’s RBC’s with Coombs serummaternal Ab present if cells agglutinate

Non Reliable Parameters:• Placental thickness• Umbilical vein diameter• Hepatic size• Splenic size• Polyhydramnios

Visualization of walls of fetal bowel from small amounts intra abdominal fluid may be 1st sign of impending hydrops

U/S reliable for hydrops (ascites, pleural effusions, skin edema) – Hgb < 70

Ultrasound Parameters

COMPLICATIONS

DURING PREGNANCY•Mild anemia,

hyperbilirubinemia and jaundice.• Severe anemia with

enlargement of the liver and spleen. •Hydrops fetalis.

AFTER BIRTH• Severe

hyperbilirubinemia and jaundice. •Kernicterus

Management

• Anti D immunoglobulin• Fetal blood transfusion (fetal Hct <30%)• Phototherapy

• Routes of administration-• Into umbilical vein at the point of cord insertion• Into intrahepatic vein• Into peritoneal cavity• Into fetal heart

• Transfused blood-• RhD negative• Crossmatched with a maternal sample• Densely packed (Hb around 30g/L)• White cell depleted and irradiated• Screened for infection including CMV

•Prophylactic vaccinations-• During every pregnancy• After a miscarriage or abortion• After prenatal tests such as amniocentesis and chorionic villus

biopsy• After injury to the abdomen during pregnancy