Rhesus Disease and Fetal Hydrops

Question 1

Explain the general principle of how rhesus disease occurs?

Answer 1

Rhesus negative anti D mother.

1st child is Rh positive during child birth mixing of blood.

Mother develops Anti Rh D antibodies.

During second pregnancy these antibodies can cross the placenta, if the second child is Rh D +ve then these antibodies will attack the fetal red blood cells.

This will cause haemolysis resulting in:
-Neonatal jaundice and anaemia
OR
-If severe fetal hydrops and fetal death

Question 2

What is the principle of rhesus isoimmunisation?

Answer 2

At 28 weeks a blood group and antibody screen is performed.

If the women tests positive for anti D then they should be given anti D prophylaxis.

Should also be given to women who have had potentially sensitising events ideally within 72hrs of event.

Question 3

What events are classed as sensitising with regards to developing anti D Ig?

Answer 3

• Invasive prenatal diagnosis - eg, amniocentesis.
• Antepartum haemorrhage.
• ECV
• Ectopic pregnancy.
• Any intrauterine procedures (eg, insertion of shunts, embryo reduction, evacuation of molar pregnancy.)
• Miscarriage, intrauterine death and stillbirth.
• Therapeutic termination of pregnancy.

Question 4

If rhesus disease is discovered in a foetus how can the anaemia be treated in utero?

Answer 4

Transfuse packed red cells into the umbilical vein.

Only do this from 18 weeks onwards.

Treatment can be repeated every 2weeks, note after 35 weeks delivery is preferable.

Question 5

What are the other main 2 antibodies which can cause haemolysis in the new born?

Answer 5

Anti c
Anti kell

ABO disease can also commonly cause haemolysis although is not usually as severe.

Question 6

What is fetal hydrops?

Answer 6

Fetal hydrops is abnormal accumulation of fluid in 2 or more fetal compartments.

Essentially it is oedema in a foetus.

Question 7

In moderate fetal hydrops what will happen?

Answer 7

In utero:
Products of RBC production are transferred across the placenta to the maternal circulation to be metabolised so there are few problems in utero.

Postnatal:
They will have jaundice have a relatively high risk for developing kernicterus (90% mortality + significant morbidity).

Will have a moderate degree of anaemia.

Question 8

In severe fetal hydrops what will happen?

Answer 8

Severe anaemia with erythropoiesis from liver and spleen..

Pleural effusions.

Ascites and hepatosplenomegaly.

Anasarca (whole body oedema)

Boggy oedematous placenta.

Question 9

What are the maternal complications of severe fetal hydrops?

Answer 9

Polyhydraminos
Anaemia
Increased risk of pre-eclampsia
PPH 
Retained placenta

Question 10

What are the non immune related (e.g. rhesus disease) causes of fetal hydros?

Answer 10

• Idiopathic 60%
• Cardiac abnormalities 20-35%
• Chromosomal
• Haemolytic diseases (thalassemia major, G6DPH deficiency)
• Infection
• Twin to twin transfusion