Rho(D) immune globulin: Nursing pharmacology

RhO (D) immune globulin, or RhIG for short, is a biological class of medications primarily used in the management of Rh-negative pregnancies, which occur when the client has Rh-negative blood, while the fetus has Rh-positive blood.

The first Rh-negative pregnancy is usually not associated with complications, but in the following pregnancies, this Rh incompatibility can cause severe, life-threatening fetal complications.

What happens is that during delivery of the first Rh-negative pregnancy, some of the baby’s red blood cells can get into the client’s circulation.

Now, since the mother has Rh-negative red blood cells, her immune system recognizes the baby’s Rh-positive red blood cells as foreign, and triggers the production of anti-Rh antibodies.

At first, the mother produces IgM antibodies, which are too big to cross the placenta, therefore there are no complications during the first pregnancy.

But, over time, the mother develops IgG anti-Rh antibodies, which are smaller. As a result, if another Rh-negative pregnancy occurs, these preformed IgG antibodies are able to cross the placenta and destroy the fetal Rh-positive red blood cells.

This process is called Rh isoimmunization, and ultimately causes hemolytic disease of the fetus and newborn, or HDFN for short.

In order to prevent Rh isoimmunization, all pregnant clients with Rh-negative blood should be given RhO (D) immune globulin, which can be administered intramuscularly.

Once RhO (D) immune globulin is administered, it suppresses the mother’s immune response and antibody formation against the fetus.

In fact, if the mother receives RhO (D) immune globulin within 72 hours postpartum, the chances of Rh isoimmunization drop to 1 or 2%.

Moreover, if the mother receives RhO (D) immune globulin at 28 weeks of gestation, and then again within 72 hours after the delivery, the chance of developing Rh isoimmunization becomes less than 1%!

Unfortunately, RhO (D) immune globulin is not effective when a client has already developed a positive antibody titer to the Rh antigen.

Finally, it’s important to note that mixing of maternal and fetal blood can occur during some obstetric complications, such as abortion, ectopic pregnancy, and placental abruption; as well as with some invasive obstetric procedures, like amniocentesis.

These cases also require the administration of RhO immune globulin to prevent the possible formation of IgG anti-Rh antibodies.

Now, the most common side effects associated with RhO (D) immune globulin administration include headache, drowsiness, and dizziness, as well as vasodilation, hypotension, or hypertension.

Additionally, clients might develop reactions at the injection site such as erythema, mild pain and discomfort.