Makindo Medical Notes

Test for anti-D antibodies in all Rhesus-negative mothers at booking, 28-, and 34-weeks gestation.

About

• Rhesus haemolytic disease, also known as Hemolytic Disease of the Newborn (HDN), occurs when maternal antibodies attack fetal red blood cells, leading to haemolysis.
• This condition typically occurs when a Rhesus-negative mother carries a Rhesus-positive fetus, inherited from a Rhesus-positive father.
• The risk of haemolytic disease increases with each subsequent pregnancy due to maternal sensitization to Rhesus antigens.

Aetiology

• First Pregnancy: A Rhesus-negative mother exposed to Rhesus-positive fetal blood during delivery may develop anti-D IgG antibodies.
• Subsequent Pregnancies: IgG anti-D antibodies can cross the placenta, leading to haemolysis in Rhesus-positive fetuses.
• In a smaller subset of cases, alloimmunisation may occur with other antigens (c, C, d, D, e, E) or through incompatible Kell, Duffy, or ABO blood group systems, though anti-D remains the most common cause.

Clinical Features

• In severe cases, the condition can lead to hydrops fetalis, characterized by severe fetal anaemia, ascites, and generalized oedema.
• Newborns may present with jaundice and severe anaemia soon after birth, and untreated cases are at risk of kernicterus, a form of brain damage due to high bilirubin levels.
• Enlargement of the liver and spleen, as well as respiratory distress, may occur in severe cases.

Investigations (Follow Local Protocols)

• Anti-D antibody levels:
  • Anti-D antibody < 4 U/ml: Generally considered low risk for complications.
  • Anti-D antibody > 4 U/ml: Regular ultrasound scans (USS) are advised to monitor fetal health.
  • Anti-D antibody > 10 U/ml: Specialized consultation and monitoring for possible intervention.
• Fetal Hemoglobin (Hb): A fetal Hb level < 7 g/dl suggests severe anaemia and the need for urgent intervention.
• Ultrasound: Assess for signs of fetal hydrops, including ascites, pleural effusions, and polyhydramnios.
• Middle Cerebral Artery (MCA) Doppler: Increased peak systolic velocity in the MCA can indicate fetal anaemia.

Management

• Screen all Rhesus-negative mothers for anti-D antibodies at booking, 28 weeks, and 34 weeks of gestation.
• For Neonates with Haemolytic Disease:
  • Consider exchange transfusion and intense UV phototherapy to reduce bilirubin levels.
  • In cases of hydrops fetalis, manage with neonatal ventilation, transfusion for severe anaemia, treatment of hypoglycaemia, and drainage of ascites and pleural effusions as needed.
  • Supportive treatments include administering Vitamin K to prevent bleeding and Furosemide for fluid management if indicated.
• Preventive Measures:
  • Administer Rh immunoglobulin (anti-D) to Rhesus-negative women during pregnancy (around 28 weeks) and shortly after delivering a Rhesus-positive baby to prevent sensitization.
  • If there is any bleeding or trauma during pregnancy, administer additional doses of Rh immunoglobulin as per protocol.