Postnatal Cytomegalovirus (CMV) Testing in the Neonatal Intensive Care Unit (NICU): Why?

Background: The spectrum of postnatally-acquired CMV infection in preterm (PT) infants can range from clinically inapparent infection to severe disease. Reason(s) for evaluation of PT infants for possible acquired CMV infection is not fully known.

Methods: Retrospective review of all CMV PCR tests or cultures performed by the Virology Laboratory at Nationwide Children’s Hospital from 2008-2014. Infants in the NICU who had CMV testing from any body fluid or site after 21 days of age were identified, their electronic health records were reviewed for clinical and laboratory data, and the reason(s) for CMV testing was determined.

Results: During the 7 year study period, 5414 infants were admitted to the NICU and 153 (3%) were tested for CMV (20 [13%] positive). The median (interquartile range [IQR]) birth weight and gestational age among CMV-infected and uninfected infants were 769 (611-2436) g and 26 (25-35) wks and 845 (643-1890) g and 27 (25-33) wks, respectively. The majority were tested by PCR; only 4 were tested by viral culture. Sites of testing included urine, blood, CSF, bronchoalveolar lavage, and tracheal aspirate, with urine being the most common site. Among the 133 infants who had a negative CMV test, the most common reasons for testing were direct hyperbilirubinemia (n=45), thrombocytopenia (n=40), or transaminitis (n=20). Additional indications for testing included evaluation for sepsis, pulmonary symptoms, anemia, neutropenia, poor growth, abnormal head imaging, microcephaly, IUGR, hepatomegaly, and positive CMV testing in a sibling. In the 20 CMV-infected infants, hyperbilirubinemia (n=10) and thrombocytopenia (n=8) were the most common indications. Referral on the newborn hearing screen was the indication for testing in only 4 patients (all negative). Among those infants who tested negative, 7 were tested on more than one occasion.

	CMV positive (%)	CMV negative (%)	p-value
No. of infants	20	133
Direct hyperbilirubinemia	10 (50)	45 (34)	0.21
Thrombocytopenia	8 (40)	40 (30)	0.44
Transaminitis	2 (10)	20 (15)	0.74

Conclusion: Both CMV testing (3%) and detection (0.4%) were infrequent among PT infants >21 days of age in the NICU. However, when suspected, CMV was detected in 13% of evaluations. Prospective studies involving targeted newborn screening and follow-up testing for possible signs of acquired disease are urgently needed.