Fetal Anaemia & Rh Disease

The most frequent causes are:

• Rh Iso-immunization: If an Rh-negative mother is carrying an Rh-positive baby, her immune system may create antibodies that cross the placenta and destroy the baby's red blood cells.
• Viral Infections: Parvovirus B19 (Slapped Cheek Syndrome) can temporarily stop the baby's bone marrow from producing new red blood cells.
• TAPS (in Twins): A chronic transfusion between identical twins (see TAPS article).

When a baby is anaemic, their heart pumps faster and their blood becomes 'thinner' and moves more quickly. We use this principle to measure the anaemia non-invasively.

• Blood Group: Women with Rh-negative blood types (A-, B-, AB-, O-) or those with known rare antibodies (like Kell or Duffy).
• Exposure: Teachers, healthcare workers, or parents of toddlers who may be exposed to Parvovirus B19.
• Previous History: If a previous baby was born jaundiced or required a transfusion after birth.

Screening for antibodies is a standard part of every woman's first-trimester blood tests.

The modern standard for diagnosing fetal anaemia is MCA-PSV Doppler (Middle Cerebral Artery Peak Systolic Velocity).

By measuring the speed of blood flow in the baby's brain, we can accurately predict how anaemic the baby is without ever touching the baby. If the measurement is above a certain threshold (1.5 Multiples of the Median), it indicates severe anaemia. We may then perform a cordocentesis (taking a blood sample from the umbilical cord) to confirm the exact hemoglobin level before proceeding with a transfusion.

The definitive treatment is Intrauterine Transfusion (IUT):

• The Procedure: Under continuous ultrasound guidance, a fine needle is placed through the mother's abdomen and into the baby's umbilical vein. Pure, cross-matched, O-negative blood is then slowly transfused into the baby.
• The Effect: The baby's heart rate stabilizes, and if hydrops was present, it often begins to resolve within days.
• Timing: IUT can be performed as early as 16-18 weeks and repeated every few weeks until the baby is mature enough for delivery (usually around 34-35 weeks).

The survival rate for babies treated with IUT for Rh disease or infection is very high—typically over 95%.

• These babies do not have long-term health issues related to the anaemia once they are born and treated.
• They may require Phototherapy (light treatment) for jaundice or an additional blood transfusion in the first weeks of life, but they eventually go on to live completely normal, healthy lives.
• In the past, this condition was a major cause of stillbirth; today, it is a triumph of modern fetal therapy.

If you are Rh-negative and your 'antibody titers' are rising, or if a scan shows your 'baby's brain Doppler is high,' you must be seen by a subspecialist immediately.

Performing an IUT is a highly skilled procedure that requires a coordinated team. Our consultants, led by Dr. Ali Al-Ibrahim, have performed hundreds of these procedures and provided the regional expertise needed to manage complex blood group incompatibilities safely.