Isoimmunization or Rh Incompatibility occurs when a mother with Rh-negative or a missing Rh-(D) factor (Rh factor is an antigen that is found on red blood cell) is carrying a fetus who is Rh-Positive. Any woman who is Rh-negative with a partner who is Rh-positive is at risk of producing a baby with a positive Rh factor.

 

People who are Rh-Positive usually have antigen (D) while those with Rh-negative do not have it. During pregnancy, if the mother is sensitized (mother has already produced antibodies against the Rh-positive fetus), this causes the mother's body to react as if it has been invaded by a by foreign body, just the same way it can reacts when invaded by a bacteria or a virus.

 

As a result, the antibodies attack the invading foreign body (fetal Rh-factor) and then crosses the the placenta, destroying the fetal red blood cells (hemolysis of the fetal red blood cells).

 

When this happens, the red blood cells are decreased in number and the fetus cannot get adequate oxygen needed to maintain the body cells. This is what is called hemolytic disease of the new born or erythroblastosis fetalis.

 

In normal circumstance, the maternal blood does not mix with the fetal blood and only happens during certain invasive procedure such as; amniocentesis, abortion. This can lead to an active exchange of maternal and fetal blood, putting the second pregnancy at risk. 

 

Antibodies Pregnancy Test

Anti-D antibody titer tests are done at first pregnancy visit for all woman with Rh-negative. If the results are normal or minimal, the test is repeated again after 28 weeks. If the results are still normal at this time, no intervention is needed.

 

If the woman anti-D antibody is high by the time the first test is done and it shows Rh sensitization, the fetus is monitored every 2 weeks or even after every 1 week to access development of anemia. Depending on the results and the status of fetus, an immediate birth may be necessary or an intra uterine blood exchange may be ordered. Sometimes, labor induction may be indicated even if the fetus is pre-term.

 

Rh Negative Treatment and Management

To decrease the number of Rh (D) antibodies that is been produced by the woman, a Rh (D) immune globulin (RhIG) is adminstered at 28 weeks of pregnancy. After birth, the RhIG is usually injected within the first 72 if the mother delivered a Rh-positive baby to prevent the mother from forming natural antibodies. If the newborn blood has Rh-negative that means there is no antibodies that have been formed and no need of administering the RhIG to the mother.

 

The other way to manage this condition is through intrauterine blood transfusion. The blood is transfused while the fetus is still in the uterus by injecting blood directly to a vessel in a fetal cord. This is done to restore the red blood cells. After birth, the fetus may have to undergo another blood transfusion to get rid of the affected blood cells (hemolyzed blood) and replace them with normal health red blood cells.

 

Complication Associated with Intrauterine Blood Transfusion