Fetal transfusion

Why is this done?

The majority of fetal transfusions are performed for two reasons.

Haemolytic disease of the fetus: this is a condition where the mother or pregnant person produces blood cell antibodies which cross the placenta and destroy the baby's blood. Fetal transfusion is sometimes necessary for the pregnancy to continue until term. The condition will resolve naturally after the baby's birth.

Infection: the commonest infection is from a virus named parvovirus B19. This virus causes a harmless infection in most children and adults called 'slapped cheek'. However, if parvovirus is contracted during pregnancy, there is a 1 in 20 chance that the baby may become anaemic as a result. The baby might require a fetal transfusion, but in most cases the infection will resolve without other consequences.

How is a fetal transfusion performed?

This is performed as a daytime procedure under local anaesthetic and does not usually require hospital admission.

A couple of days before the procedure you will have a blood test so that our blood bank can select and prepare the appropriate blood type for your baby's transfusion. On the day of the transfusion we will offer you an antibiotic injection in order to minimise the risk of infection.

The procedure will be performed under direct ultrasound vision. The fetal medicine specialist will introduce a thin needle through the skin of your tummy into a blood vessel of the umbilical cord.

The baby's blood count will be measured before the start of the transfusion in order to estimate how much blood is needed, and also at the end in order to confirm that the correct volume of blood was given.

When transfusions are performed for haemolytic disease, a repeat transfusion is often needed every two to four weeks until the baby's birth. Less common types of transfusion are directly into the baby's heart (intracardiac) or inside the baby's tummy (intraperitoneal).

What are the risks of a fetal transfusion?

According to the UK Blood Transfusion and Tissue Transplantation Service, fetal transfusion is a highly specialised area of medical practice requiring close collaboration between experts in fetal medicine, haematology and blood transfusion.

Even in the most expert hands it carries a risk of fetal death in 1 to 3 of every 100 procedures. This risk is higher when the baby is very sick at the start of the procedure (a condition called hydrops), or when the procedure is performed due to parvovirus infection.

Because this is an invasive fetal procedure, there is also a risk of premature birth.