Rhesus Disease

Pregnancy is a remarkable journey, but it can also present unique challenges. Rhesus disease, also known as haemolytic disease of the foetus and newborn (HDFN), is one such condition that can arise during pregnancy. It occurs due to an incompatibility between the mother's and baby's blood types, specifically concerning the Rhesus (Rh) factor. This comprehensive guide provides detailed information about Rhesus disease (Rh disease), its causes, symptoms, diagnosis, treatment, and prevention strategies.

Our red blood cells sometimes carry a protein called the RhD antigen. If this protein is present, you are RhD positive. If it's absent, you are RhD negative. Rhesus disease occurs when a pregnant woman who is RhD negative is carrying a baby who is RhD positive.

In such cases, the mother's immune system can recognise the baby's RhD positive blood cells as foreign. This triggers the production of antibodies, which are proteins that aim to destroy these 'foreign' cells. These antibodies can cross the placenta and attack the baby's red blood cells, leading to anaemia and other complications.

Rh hemolytic disease affects approximately 276 out of every 100,000 live births globally. This number has dropped significantly to 2.5 per 100,000 live births in developed countries due to advancements in prevention and treatment. However, in low and middle-income countries, the prevalence remains high, affecting approximately 529 out of every 100,000 live births.

To reiterate the basics, Rhesus disease happens due to an incompatibility in the Rhesus (Rh) factor – a protein found on the surface of red blood cells. Here's how it unfolds:

Rh Blood Incompatibility: The crucial factor is that the mother is Rh-negative (lacks the RhD antigen), while the baby is Rh-positive (inherits the RhD antigen from the father).

Sensitisation: This is the key event. The mother's immune system comes into contact with the baby's Rh-positive blood cells, recognizing them as foreign. This can occur during:

• Pregnancy: Small amounts of the baby's blood can enter the mother's circulation.
• Childbirth: The largest opportunity for mixing of blood occurs during delivery.
• Miscarriage or Ectopic Pregnancy: These events can also expose the mother to fetal blood.
• Amniocentesis or Chorionic Villus Sampling (CVS): Invasive prenatal testing procedures carry a small risk of mixing blood.
• Abdominal Trauma: Any injury to the abdomen during pregnancy can potentially cause blood mixing.

Antibody Production: Once sensitised, the mother's immune system produces antibodies (specifically anti-D antibodies) against the RhD antigen. These antibodies remain in her system.

Impact on Subsequent Pregnancies: In future pregnancies with an Rh-positive baby, the mother's existing anti-D antibodies can cross the placenta and attack the baby's red blood cells. This leads to the destruction of the baby's red blood cells (hemolysis), causing anemia and other complications.

Rhesus disease doesn't cause any symptoms in the mother. However, it can cause a range of problems in the baby, including:

• Anaemia: The destruction of red blood cells leads to anaemia, which can make the baby feel tired and weak.
• Jaundice: The breakdown of red blood cells produces bilirubin, a yellow substance that can cause the baby's skin and eyes to appear yellow.
• Hepatosplenomegaly: Enlargement of the liver and spleen due to their increased workload in trying to remove damaged red blood cells.
• Hydrops fetalis: A severe form of the disease where fluid builds up in the baby's tissues and organs.

Early detection is vital for managing Rhesus disease effectively. Here's how it's diagnosed:

For the Mother

• Blood Typing and Rh Factor Determination: This is a routine part of prenatal care. A blood sample is taken to determine the mother's blood type and whether she is Rh-negative or Rh-positive.
• Antibody Screening: If the mother is Rh-negative, her blood is screened for the presence of anti-D antibodies. This is usually done at the first prenatal visit and again around 28 weeks of pregnancy.

For the Baby

• Antibody Titer: If anti-D antibodies are detected in the mother's blood, the level of antibodies (titer) is measured to assess the risk to the baby.
• Amniocentesis: In some cases, amniocentesis may be performed to measure the level of bilirubin (a breakdown product of red blood cells) in the amniotic fluid. This helps determine the severity of the disease in the baby.
• Ultrasound: Ultrasound scans are used to monitor the baby's growth, development, and well-being. Signs such as an enlarged liver, spleen, or fluid buildup (hydrops fetalis) can indicate Rhesus disease.
• Doppler Ultrasound: This specialized ultrasound measures blood flow in the umbilical cord and can help assess the severity of anemia in the baby.
• Fetal Blood Sampling (Cordocentesis): In rare cases, a sample of the baby's blood may be taken from the umbilical cord to directly assess anemia and blood type.

The treatment for Rhesus disease depends on the severity of the condition and how the baby is affected.

For the Mother

• Anti-D Immunoglobulin (RhoGAM): This is the key preventative measure. It's given to Rh-negative women to prevent sensitization to Rh-positive blood cells. It's usually administered at 28 weeks of pregnancy and again within 72 hours after delivery if the baby is Rh-positive. It may also be given after any event that could cause sensitization (miscarriage, ectopic pregnancy, etc.).

For the Baby

• Monitoring: If the baby is only mildly affected, close monitoring with ultrasounds and blood tests may be sufficient.
• Intrauterine Blood Transfusion: If the baby develops severe anemia before birth, a blood transfusion may be given through the umbilical cord. This helps to correct the anemia and allow the baby to continue developing.
• Early Delivery: If the baby is mature enough and the disease is severe, early delivery may be considered to prevent further complications.
• Phototherapy: After birth, phototherapy (light therapy) is often used to help break down bilirubin in the baby's body and reduce jaundice.
• Exchange Transfusion: In severe cases, an exchange transfusion may be necessary. This involves replacing the baby's blood with Rh-negative blood to reduce bilirubin levels and correct anemia.
• Intravenous Immunoglobulin (IVIG): In some cases, IVIG may be given after birth to help reduce the levels of antibodies attacking the baby's red blood cells.

It's important to remember that with proper prevention and management, most babies affected by Rhesus disease can be born healthy and go on to live normal lives.

The main risk factor for Rhesus disease is being an RhD negative woman carrying an RhD positive baby. Other factors that may increase the risk include:

• Previous pregnancy with an RhD positive baby: The risk of sensitisation increases with each pregnancy.
• Miscarriage or ectopic pregnancy: These can also lead to sensitisation.
• Invasive prenatal procedures: Procedures like amniocentesis can increase the risk of mixing maternal and foetal blood.

Untreated Rhesus disease can lead to serious complications for the baby, including:

• Severe anaemia
• Brain damage
• Hearing loss
• Cerebral palsy

While Rhesus disease primarily affects the baby, here are some tips for parents:

1. Monitor your baby’s health closely. Regular check-ups and blood tests are essential to ensure your baby remains healthy.

2. Do not compromise on early intervention. If treatment is needed, it's crucial to receive it promptly to prevent complications.

3. Seek support from healthcare professionals and connect with other families who have experienced Rhesus disease so you are well-equipped to manage it.

It affects all pregnancies with Rh incompatibility.

Rhesus disease only occurs if the mother has been previously sensitised to RhD positive blood.

It always causes severe problems.

Many cases are mild and may not require treatment.

It can be cured.

While Rhesus disease cannot be cured, it can be effectively managed and prevented.

• If you are pregnant and have a negative blood type
• If you experience any bleeding or abdominal trauma during pregnancy
• If your baby shows signs of jaundice after birth:

• What is my Rh factor?
• What are the chances of my baby developing Rhesus disease?
• What preventative measures are available?
• What are the signs and symptoms I should watch out for?
• What treatment options are available if my baby is affected?

• Offer emotional support: Pregnancy complications can be stressful. Offer a listening ear and reassurance.
• Help with practical tasks: Offer assistance with childcare, errands, or household chores.
• Educate yourself about the condition: Learning about Rhesus disease can help you understand what they are going through.
• Connect them with support resources: Provide information about support groups or online communities.

Rhesus disease is an Rh incompatibility disease, a condition that can cause complications during pregnancy, but with preventative measures and appropriate management, most babies can be born healthy. If you are pregnant or planning a pregnancy, talk to your doctor about your Rh factor and any necessary precautions.