Haemolytic Disease of the Newborn

Question 1

Name 3 of the main causes of haemolytic disease of the newborn?

Answer 1

Rhesus disease
ABO incompatibility
Vitamin K deficiency

Question 2

Explain the pathophysiology of ABO incompatibility?

Answer 2

Most ABO antibodies are IgM and do not cross the placenta .
Women with Blood group O have an IgG anti-A-haemolysin in the blood which can cross the placenta.

If this occurs then the IgG anti A can cause haemolysis of the red cells of a group A infant. Occasionally a group B infant is affected by anti-B haemolysins.

Haemolysis can cause severe jaundice (usually less severe than in rhesus disease)

The jaundice usually peaks in the first 12-72 hours.

Question 3

Explain the pathophysiology of rhesus disease?

Answer 3

This condition occurs when a mother is rhesus- negative and gives birth to a rhesus-positive child.

This sensitises her to rhesus antigens and the mother produces antibodies.

If she gets pregnant with a rhesus positive child again then the IgG antibodies will attack the child.

Question 4

What clinical picture dose rhesus disease produce?

Answer 4

Birth of an infant with:

• anaemia
• hydrops (oedema in 2 or more compartments in a foetus or neonate)
• hepatosplenomegaly
• rapidly developing severe jaundice

Question 5

What are the major risks to a newborn of severe jaundice?

Answer 5

If there is an excess of unconjugated bilirubin that saturates the albumin then it is free to cross the BBB and deposit itself in the basal ganglia, causing kernicterus.

Kernicterus is an encephalopathy which presents as poor feeding, irritability and increased muscle tone.

If not treated promptly it can cause death or long term complications: CP, sensorineural hearing loss and LD.