Rhesus Incompatability

Question 1

Rhesus D negative

Answer 1

Lack of rhesus-D antigen present on their red blood cell surface

Question 2

Sensitisation

Answer 2

Initial rhesus D negative mother and rhesus D positive foetus blood mixing

Causes no problems during the first pregnancy

Question 3

Haemolytic disease of the newborn

Answer 3

During subsequent pregnancies, the mother’s anti-rhesus-D antibodies cross the placenta

If that fetus is rhesus-D positive, antibodies attach themselves to the RBCs of the fetus and causes immune destruction haemolysis

Question 4

Management of haemolytic disease of the newborn

Answer 4

Prevention of sensitisation - IM anti D injections to rhesus negative women

Question 5

How does anti - D work

Answer 5

Attaches itself to the rhesus-D antigens on the fetal RBCs in the mothers circulation causing haemolysis

Prevents the mother’s immune system recognising the antigen and creating it’s own antibodies to the antigen.

Prevents sensitisation

Question 6

When is anti - D given

Answer 6

Given routinely on two occasions:

• 28 weeks gestation
• Birth

Anti-D injections should also be given at any time where sensitisation may occur such as:

• Antepartum haemorrhage
• Amniocentesis procedures
• Abdominal trauma

Question 7

What is the anti D injection window

Answer 7

Anti-D is given within 72 hours of a sensitisation event.

Question 8

Kleinhauer test purpose

Answer 8

To see how much fetal blood has passed into the mother’s blood, to determine whether further doses of anti-D are required

Question 9

When is the Kleinhauer test performed

Answer 9

After 20 weeks gestation

Question 10

What does the Kleinhauer test involve

Answer 10

Involves adding acid to a sample of the mother’s blood.

Fetal haemoglobin is naturally more resistant to acid

Fetal haemoglobin persists in response to the acid, while the mothers haemoglobin is destroyed.

The number of cells still containing haemoglobin (the remaining fetal cells) can be calculated.