A full-term neonate is born with microcephaly, sensorineural hearing loss, blueberry muffin rash, and hepatosplenomegaly. Ophthalmologic examination reveals chorioretinitis. The mother had a flu-like illness with rash at 10 weeks gestation and was found to have elevated IgG avidity to cytomegalovirus. Which additional investigation would BEST confirm congenital CMV infection in the neonate?

• A CMV IgM in cord blood
• B Maternal serology confirming primary CMV infection
• C CMV IgG in neonatal blood
• D CMV DNA PCR on urine or saliva collected within the first 21 days of life ✓

Explanation

Congenital CMV infection must be confirmed by detecting the virus in the neonate, not the mother. CMV DNA PCR on urine or saliva within the first 21 days of life is the gold standard for diagnosing congenital (intrauterine) CMV, as it differentiates congenital from postnatal acquisition. After 21 days, a positive CMV PCR could represent postnatal infection acquired through breast milk or other routes. Neonatal IgG reflects maternal antibody transfer and cannot diagnose active infection. IgM can be false negative in up to 30% of congenital CMV cases.

Reference: Ghai Essential Pediatrics, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.