This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
[{'content': 'Which of the following methods can be used to detect rubella infection in children – \nSelect and explain. \nA. T4 cell count, B. Fetal hemoglobin, C. IgM antibody in fetal blood, D. IgA Antibody in fetal blood', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Laboratory diagnosis\n\nIsolation of virus in cell cultures of throat samples, urine or other secretions.\nNormally, a maternal rubella antibody in the form of IgG is transferred to infants and is gradually last over a period of 6 months. Persistent beyond I year in an unvaccinated child suggests the diagnosis of congenital rubella.\nPresence of IgM antibodies is diagnostic.\nPCR for rubella RNA.', 'role': 'assistant'}]