Which condition is characterized by immune-mediated hydrops with Rh sensitivity and findings such as scalp edema, pleural effusion, pericardial effusion, polyhydramnios, and placentomegaly?

• A. Immune hydrops
• B. Hydrops fetalis
• C. Nonimmune hydrops
• D. Placental edema

Answer: (A)

Immune hydrops is caused by maternal antibodies against fetal red blood cells, most classically anti-D in Rh incompatibility. This alloimmune attack leads to fetal anemia and high-output heart failure, which in turn causes fluid to accumulate in multiple fetal compartments. The findings described—scalp edema and effusions in the pleural and pericardial spaces, along with polyhydramnios and placentomegaly—are classic manifestations of hydrops fetalis in its immune form. Nonimmune hydrops can produce similar signs but lacks the antibody-mediated mechanism, so the Rh-sensitive immune mechanism makes immune hydrops the best fit.