A term newborn has petechiae, thrombocytopenia, periventricular calcifications and sensorineural hearing loss. Congenital cytomegalovirus infection is suspected. What is the appropriate confirmatory test at day 4 of life?
- A CMV IgG antibody from cord blood
- B PCR for CMV DNA in urine or saliva collected before 3 weeks of age ✓
- C CMV IgM antibody from maternal serum
- D Serum pp65 antigenemia assay
Correct answer: B. PCR for CMV DNA in urine or saliva collected before 3 weeks of age
Explanation
Congenital CMV is confirmed by detecting viral DNA in urine or saliva by PCR within the first three weeks of life, since later positivity may reflect postnatal acquisition through breast milk. Maternal IgG crosses the placenta and cannot diagnose neonatal infection, while neonatal IgM is insensitive. The pp65 antigenemia assay requires adequate blood volume and leukocytes and is largely superseded by PCR in this setting.
Reference: Nelson Textbook of Pediatrics, 22nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.