Rhesus (Rh) factor

The Rh factor is an important protein found on the surface of red blood cells in many individuals. People who have this protein are considered Rh-positive, while those who lack it are Rh-negative. The Rh factor is a key component of blood typing, which includes both the ABO and Rh systems. It plays a significant role in blood transfusions, organ transplants, and pregnancy, as incompatible Rh factors between mother and fetus can lead to Rh incompatibility issues. Understanding a person’s Rh status is essential for safe medical treatments and maternal-fetal health.

1.0Introduction

Blood typing is determined by the molecules on the surface of the red blood cells (RBCs). In general, we can classify someone’s blood type by the absence or presence of A or B antigens and Rh factor on the surface of blood cells. The most commonly recognized blood groups are A positive, A negative, B positive, B negative, AB positive, AB negative, O positive, and O negative.The positive or negative sign next to the blood groups is known as the Rhesus (Rh) factor. The Rh factor is an inherited protein that can be found on the surface of the red blood cell. If  blood group type is positive, then blood cells have the Rh protein. If  blood group type is negative, then  blood cells lack the Rh protein. 

2.0Rh incompatibility(Erythroblastosis fetalis)

Rh incompatibility is a condition that develops when a pregnant woman has Rh-negative blood and the baby in her womb has Rh-positive blood.

Causes

• During pregnancy, red blood cells from the unborn baby can cross into the mother's blood through the placenta.
• If the mother is Rh-negative, her immune system treats Rh-positive fetal cells as if they were a foreign substance. The mother's body makes antibodies against the fetal blood cells. These antibodies may cross back through the placenta into the developing baby. They destroy the baby's circulating red blood cells.
• When red blood cells are broken down, they make bilirubin. This causes an infant to become yellow (jaundiced). The level of bilirubin in the infant's blood may range from mild to dangerously high.
• Firstborn infants are often not affected unless the mother had past miscarriages or abortions. This would sensitize her immune system. This is because it takes time for the mother to develop antibodies. All children she has later who are also Rh-positive may be affected.
• Rh incompatibility develops only when the mother is Rh-negative and the infant is Rh-positive. This problem has become less common in places that provide good prenatal care. This is because special immune globulins called RhoGAM are routinely used.

Symptoms

• Rh incompatibility can cause symptoms ranging from very mild to deadly. In its mildest form, Rh incompatibility causes the destruction of red blood cells. There are no other effects.

After birth, the infant may have:

• Yellowing of the skin and whites of the eyes (jaundice)
• Low muscle tone (hypotonia) and lethargy

Complications may include:

• Brain damage due to high levels of bilirubin (kernicterus)
• Fluid buildup and swelling in the baby (hydrops fetalis)
• Problems with mental function, movement, hearing, speech, and seizures

Treatment

• Rh incompatibility can be prevented with the use of RhoGAM. Therefore, prevention remains the best treatment. Treatment of an infant who is already affected depends on the severity of the condition.
• Infants with mild Rh incompatibility may be treated with phototherapy using blue  lights., IV immunoglobulin may also be used. For infants severely affected, an exchange transfusion of blood may be needed. This is to decrease the levels of bilirubin in the blood.

Prevention

• Rh incompatibility is almost completely preventable. Rh-negative mothers should be followed closely by healthcare providers during pregnancy.
• Special immunoglobulins, called RhoGAM, are now used to prevent RH incompatibility in mothers who are Rh-negative.
• If the father of the infant is Rh-positive or if his blood type is not known, the mother is given an injection of RhoGAM during the second trimester. If the baby is Rh-positive, the mother will get a second injection within a few days after delivery.

These injections prevent the development of antibodies against Rh-positive blood. However, women with Rh-negative blood type must get injections:

• During every pregnancy
• After a miscarriage or abortion
• After prenatal tests such as amniocentesis and chorionic villus biopsy
• After injury to the abdomen during pregnancy