In which of the following clinical scenarios Anti D prophylaxis is not recommended?
**Core Concept**
Anti-D prophylaxis is administered to prevent RhD alloimmunization in RhD-negative women who are exposed to RhD-positive fetal blood during pregnancy or childbirth. This is crucial to prevent the development of anti-RhD antibodies, which can lead to hemolytic disease of the newborn in future pregnancies.
**Why the Correct Answer is Right**
Anti-D prophylaxis is not recommended in cases where the RhD status of the fetus is known to be RhD-negative, as there is no risk of RhD-positive fetal blood entering the maternal circulation. This is typically determined through amniocentesis or cordocentesis, where fetal blood sampling is performed. Administering Anti-D prophylaxis in such cases would be unnecessary and may even cause harm by inducing an immune response.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because Anti-D prophylaxis is recommended for RhD-negative women who have an RhD-positive fetus, as there is a risk of fetal-maternal hemorrhage during pregnancy or childbirth.
**Option B:** Incorrect because Anti-D prophylaxis is not contraindicated in RhD-negative women with a history of previous RhD alloimmunization; rather, it is essential to prevent further sensitization.
**Option C:** Incorrect because Anti-D prophylaxis is recommended for RhD-negative women who have an RhD-positive fetus, regardless of whether they have a history of previous sensitization.
**Clinical Pearl / High-Yield Fact**
Anti-D prophylaxis should be administered within 72 hours of suspected fetal-maternal hemorrhage, and a second dose should be given at 28 weeks of gestation in RhD-negative women with an RhD-positive fetus.
**Correct Answer: D.**