Rhesus haemolytic disease

Question 1

How is rhesus status shown?

Answer 1

Rh(D) status of an individual is normally described with apositiveornegativesuffix after theABOtype. e.g. Someone who is A Positive has the A antigen and the Rh(D) antigen, whereas someone who is A Negative lacks the Rh(D) antigen.

Question 2

What is the physiology behind rh haemolytic disease

Answer 2

When a RhD -ve mum delivers RhD +ve baby a leak of fetal red cells into her circulation may stimulate her to produce anti-D IgG abs (isoimmunisation)
In subsequent pregnancies, these can cross the placenta causing worsening Rh haemolytic disease w each successive Rh+ve pregnancy

Question 3

What can precipitate this?

Answer 3

• Threatened miscarriage
• APH
• Mild trauma
• Amniocentesis
• Chorionic villus sampling
• External cephalic version

Question 4

How can it present in the fetus?

Answer 4

1. Hydrops fetalis - oedematous as liver is devoted to RBC production albumin falls
2. Jaundice, anaemia, hepatosplenomegaly
3. CCF - oedema and ascites
4. Kernicterus

Question 5

What are the DDs?

Answer 5

thalassaemia
infection
maternal diabetes

Question 6

How is rhesus haemolytic disease diagnosed?

Answer 6

1. FBC, blood group + direct Coombs test of cord blood at delivery
2. Kleihauer test - measure the amount of fetal hb thats gone into mums blood stream

Question 7

How is rhesus disease prevented?

Answer 7

1. test for D abs in all Rh -ve mothers at booking

2. Anti-D to non-sensitised Rh-ve mums at 28 and 34 weeks

Question 8

What is management if an event occurs in 2nd/3rd trimester?

Answer 8

give large dose of anti-D and perform Kleihauer test - determines proportion of fetal RBCs present

Question 9

When should anti-D Ig be given ASAP (within 72hrs?)

Answer 9

• Delivery of a Rh +ve infant, whether live or stillborn
• Any termination of pregnancy
• Miscarriage if gestation is > 12 weeks
• Ectopic pregnancy (only if managed surgically)
• External cephalic version
• Antepartum haemorrhage
• Amniocentesis, chorionic villus sampling, fetal blood sampling

Question 10

When are transfusions required?

Answer 10

If Hb <7g/dL give 1st volume of the exchange transfusion as packed cells and subsequent precise exchanges according to response

Question 11

When is phototherapy required?

Answer 11

in milder disease