Who Let The Doc Out?! #008: Rhesus factor incompatibility in pregnancy

Every human being has a blood type. There are several different blood typing systems, but the most commonly used one is the ABO system (blood types A, B, AB, and O). Under the ABO system, a person can either be Rhesus-positive (RhD+) or Rhesus-negative (RhD-).

During pregnancy, the focus on blood group testing lies primarily on the Rh factor as a pregnant woman’s Rh factor may play a role in the health of the unborn child.

The Rhesus factor is a protein that can be found on the surface of red blood cells. If your red blood cells have this protein, then you are Rh-positive. If your red blood cells do not have this protein, you are Rh-negative.

What is Rh incompatibility?

While people who are Rh-positive will not encounter any problems if they receive blood from a Rh-negative person, the reverse is not true. If an Rh-negative person receives Rh-positive blood, their body will react by producing antibodies to defend against the foreign Rh factor. This can cause a transfusion reaction, which can be fatal if severe.

The same thing can occur in pregnancy. If an Rh-negative woman becomes pregnant by an Rh-positive man, there is a 50/50 chance that the fetus will be either Rh-negative or Rh-positive. If the fetus is Rh-negative, there are no issues as the mother and fetus are Rh compatible. However, if the fetus is Rh-positive, the mother and fetus are Rh incompatible, and this presents a problem.

Why is Rh incompatibility dangerous?

Maternal blood does not usually mix with fetal blood during pregnancy. However, a small amount of the fetal blood can come into contact with maternal blood in cases of:

  • Bleeding during pregnancy
  • Amniocentesis or chorionic villus sampling (CVS)
  • Abdominal trauma
  • During labor and delivery
  • Miscarriage or abortion
  • Ectopic pregnancy

When this happens, the mother’s body recognizes the fetus’s Rh-positive blood as a foreign body and will try to destroy it by creating anti-Rh antibodies. For the first pregnancy, these antibodies are not usually a concern because the mother’s body does not have a chance to develop a lot of antibodies. However, if treatment is not given during the first pregnancy and the mother later gets pregnant with an Rh-positive baby, her body will produce more antibodies, and this puts the fetus at risk.

Complications of Rh incompatibility

During pregnancy, the anti-Rh antibodies produced by the mother’s body can cross the placenta and attack the Rh proteins on fetal red blood cells. When this happens, the red blood cells are destroyed, causing a serious type of anemia in the fetus called hemolytic anemia, and this can be fatal.

Other complications due to Rh incompatibility include:

  • Jaundice
  • Liver failure
  • Heart failure
  • Brain damage

How to treat Rh incompatibility

The complications caused by Rh incompatibility can be prevented with treatment. The main goal of treatment is to stop Rh-negative women from developing Rh antibodies in the first place. This is done by:

  • Finding out if a pregnant woman is Rh-negative early in the pregnancy.
  • Giving medications to prevent the formation of anti-Rh antibodies.

The medication that keeps the body from making anti-Rh antibodies is known as Rh immunoglobulin (RhIg) or anti-D immunoglobulin. It is given when:

  • you are 28 weeks pregnant.
  • you deliver and your baby is confirmed to be Rh-positive. It must be given within 72 hours after delivery.
  • you undergo certain procedures like amniocentesis or chorionic villous sampling during your pregnancy
  • you experience abdominal trauma or bleeding during the pregnancy
  • you have had an ectopic pregnancy, miscarriage, or abortion
  • attempts were made to manually turn a fetus from breech presentation

The immunoglobulin injection is given with each pregnancy.

What to do if Rh antibodies are already created

If antibody screening is done and finds that Rh antibodies have already been made by the mother’s body, RhIg is ineffective. The only way to ensure the fetus’s wellbeing is through close monitoring during the pregnancy by Doppler ultrasonography. This allows your doctor to tell if the fetus’s blood is thinner and flowing more quickly, which can be a sign of anemia.

In such cases, a procedure called fetal blood sampling (FBS) is done to assess if the fetus is anemic. Under local anesthesia, a needle is inserted through your abdomen to reach the fetus and draw blood. If the fetus is found to be severely anemic, they may receive a blood transfusion through the same needle, a procedure known as Intra Uterine Transfusion (IUT).

Innocent Immaculate Acan is a medical doctor and writer currently working at Adjumani Hospital. She won the Writivism Short Story Prize in 2016 and has published an illustrated children’s book titled The Pearl Trotters in Black, Yellow, Red. She was part of the 2018 class of the Young and Emerging Leaders Project.

Innocent Immaculate Acan