Which test detects a fetal-maternal hemorrhage?

• A. Alpha-Fetoprotein
• B. Fetal Fibronectin
• C. Kleihauer-Betke
• D. Placental Lactogen

Answer: (C)

Detecting fetal-maternal hemorrhage relies on identifying fetal red blood cells in the maternal circulation. The Kleihauer-Betke test does this by treating a maternal blood smear with acid; fetal red cells resist the acid and stay stained pink/red, while most maternal red cells lose their color. By counting the proportion of fetal cells, you can estimate how much fetal blood is present in the mother’s bloodstream, which helps determine the appropriate Rh immune globulin dosing after events like delivery, amniocentesis, trauma, or miscarriage. The other tests shown don’t detect FMH: alpha-fetoprotein screens for fetal neural tube defects, fetal fibronectin predicts risk of preterm birth, and placental lactogen reflects placental function but is not used to detect fetal-maternal hemorrhage.