OB Nursing Review: What is the Coombs Test for Rh Factor?

Newborn baby on a table immediately after birth with the umbilical clamp

For nursing students, the Coombs test for Rh factor in pregnant women can be quite confusing. To understand precisely what how the Coombs test works and what Rh factor is, we’ll be discussing that in this article.

The Immune System

First, we have to know what happens inside the body to call for a Coombs test.

The immune system creates antibodies to shield the body from harmful elements like bacteria and viruses that could cause illnesses and diseases. Antibodies are designed to protect; however, on certain occasions, they are the ones causing the distress by mistakenly targeting the healthy cells inside the body.

Because not everyone’s blood cells are the same, especially red blood cells, the immune system is programmed to attack any signs of incompatibility occurring inside the body. This is where the Coombs test comes in. In specific cases, the Coombs test is done for Rh factor during pregnancy.

The Coombs Test

The Coombs test simply meant to check the blood of the mother and fetus to determine what type of Rh factor they have, whether it’s a negative or a positive Rh factor. The Coombs test will also trace of antibodies attacking the red blood cells.

Rh Factors Explained

Rh factors pertain to the type of blood the expectant mother and the fetus have. The mom can either have a negative or a positive Rh factor and whatever the Rh factor the mom has may or may not have a direct effect on the baby.

If the mother has a negative Rh factor and the baby has a positive Rh factor, the mother’s body will recognize that the baby’s blood is different from hers, thereby triggering the creation of antibodies against the baby’s positive antigen. The antibodies created will mix into the baby’s system and attack the red blood cells either before or after childbirth. This process is harmful, and at times, life-threatening for the baby.

Mom Makeover

To turn things around, mothers who have Rh-negative blood will need a makeover through the administration of RhoGAM because we have to cease this unwanted attack by her antibodies to her Rh positive baby.

For the mom, RhoGAM acts as a shield against the Rh negative blood, which in turn, protects the baby.

Tricky Exams

During major nursing exams and even the NCLEX®, this part of the test will be quite tricky because examiners love to test their students to determine if they really understand what the Coombs test is and how it is applied with the Rh factors of both mom and fetus.

Questions about the Coombs test and Rh factor will usually revolve around: What is the Coombs test for and is it meant to protect the mom or the baby?

The answer is:

The Coombs test just shows who between the mom and the child are Rh negative or Rh positive. If the mother is negative, that will be harmful to a positive Rh blood baby. The Coombs test is meant to protect the baby by shielding the mom of the antibodies that will affect the baby by giving the mom RhoGAM. Therefore, this entire process is meant to protect the fetus and not the mother.