A fetus at 26 weeks gestation develops severe hydrops fetalis with placentomegaly. Maternal serology shows recent parvovirus B19 infection. What is the mechanism by which this virus produces fetal hydrops?

• A Destruction of myocardial cells causing heart failure
• B Infection and lysis of erythroid precursors causing severe anemia ✓
• C Placental vasculopathy causing fetal hypoxia
• D Hepatic fibrosis causing portal hypertension and ascites

Explanation

Parvovirus B19 targets the P antigen on erythroid progenitor cells, causing their apoptosis and producing profound fetal anemia. The resulting high-output cardiac failure leads to hydrops fetalis, often with elevated middle cerebral artery peak systolic velocity on Doppler. Intrauterine transfusion is the treatment for severe cases. Myocarditis is described occasionally but is not the principal mechanism, and neither placental vasculopathy nor hepatic fibrosis explains the anemia-driven picture.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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