A 3rd gravida with normal previous 2 pregnancies. Best test to diagnose Rh sensitization in Rh -ve mother is
**Core Concept**
Rh sensitization occurs when an Rh-negative mother is exposed to Rh-positive fetal red blood cells during pregnancy, childbirth, or abortion. This triggers an immune response, producing antibodies that can attack future Rh-positive pregnancies.
**Why the Correct Answer is Right**
The best test to diagnose Rh sensitization in an Rh-negative mother is the Direct Coombs Test (also known as the Direct Antiglobulin Test, DAT). This test detects the presence of maternal antibodies against Rh-positive red blood cells on the surface of the mother's red blood cells. The DAT is a critical diagnostic tool for identifying Rh sensitization, which can lead to severe hemolytic disease of the newborn (HDN) in subsequent Rh-positive pregnancies.
**Why Each Wrong Option is Incorrect**
**Option A:** The Indirect Coombs Test (also known as the Indirect Antiglobulin Test, IAT) detects the presence of maternal antibodies against Rh-positive red blood cells in the mother's serum, but it is not the best test for diagnosing Rh sensitization.
**Option B:** The Kleihauer-Betke test is used to detect fetal-maternal hemorrhage, which can lead to Rh sensitization, but it is not a direct test for diagnosing Rh sensitization.
**Option C:** The maternal serum screening tests, such as the triple screen, are used to detect risks of chromosomal abnormalities and neural tube defects, but they are not relevant to diagnosing Rh sensitization.
**Clinical Pearl / High-Yield Fact**
Rh sensitization can occur even with a normal previous pregnancy, so it's essential to perform a DAT on all Rh-negative mothers after each delivery, regardless of the pregnancy outcome.
**Correct Answer: D. Direct Coombs Test (DAT).**