Makindo Medical Notes

🧾 About

• Rhesus Haemolytic Disease (Hemolytic Disease of the Newborn, HDN) occurs when maternal antibodies cross the placenta and destroy fetal red blood cells.
• Most often due to a Rhesus-negative mother carrying a Rhesus-positive fetus (father positive).
• Sensitisation risk rises with each pregnancy if prophylaxis is not given.
• Rarely, alloimmunisation can involve other antigens (Kell, Duffy, Kidd, c/C/e), but anti-D remains the commonest cause.

⚙️ Aetiology

• First pregnancy: At delivery or miscarriage, fetal Rh-positive blood may enter maternal circulation → mother produces anti-D IgG antibodies.
• Subsequent pregnancies: Maternal anti-D IgG crosses placenta → haemolysis of fetal Rh-positive red cells.
• Other triggers: Trauma, antepartum haemorrhage, invasive procedures (amniocentesis, CVS), or transfusion errors.

🩺 Clinical Features

• Fetus: Severe anaemia → high-output cardiac failure → hydrops fetalis (ascites, pleural effusions, skin oedema).
• Neonate:
  • Severe jaundice within 24 hrs.
  • Marked anaemia, hepatosplenomegaly.
  • Risk of kernicterus if untreated (bilirubin-induced brain injury).
• Severe cases: Respiratory distress, hypoglycaemia, oedema.

🔍 Investigations (follow local protocols)

• Maternal antibody titres:
  • < 4 IU/mL → low risk.
  • > 4 IU/mL → regular USS monitoring.
  • > 10 IU/mL → specialist referral (risk of fetal anaemia).
• MCA Doppler: ↑ peak systolic velocity = fetal anaemia (non-invasive gold standard).
• USS: Look for hydrops signs (ascites, skin oedema, polyhydramnios).
• Fetal Hb: < 7 g/dL = severe anaemia → intrauterine transfusion.
• Postnatal tests: Direct Coombs test (DAT), cord Hb, bilirubin levels.

💊 Management

• Antenatal:
  • Screen all Rh-negative mothers for antibodies (booking, 28w, 34w).
  • Monitor with serial MCA Dopplers if sensitised.
  • Intrauterine transfusion: via cordocentesis if fetal anaemia detected.
• Neonatal:
  • Phototherapy: Start immediately for jaundice.
  • Exchange transfusion: If bilirubin dangerously high or resistant.
  • Supportive: Vitamin K, treat hypoglycaemia, ventilatory support if hydrops.
• Prevention:
  • Anti-D immunoglobulin: 28w + post-partum (within 72h of delivering Rh+ baby).
  • Give additional doses after sensitising events (bleeding, trauma, procedures).

💡 Teaching Pearls

• Haemolytic disease from ABO incompatibility is usually milder, often affecting first pregnancy.
• MCA Doppler has replaced amniocentesis for monitoring anaemia.
• OSCE buzzwords: hydrops fetalis, kernicterus, exchange transfusion.
• Preventable cause of neonatal morbidity → always think “did the mother receive anti-D?”

📚 References

• NICE Antenatal Care [NG201] (2021).
• RCOG Green-top Guideline 65: Management of Women with Red Cell Antibodies in Pregnancy (2014).
• Williams Obstetrics, 25th Edition.