Utility of routine urine CMV PCR and total serum IgM testing of small for gestational age infants: a single center review.

BACKGROUND: Due to the extremely low incidence of TORCH (toxoplasmosis, rubella, CMV, herpes simplex virus) infections, diagnostic testing of all small for gestational age (SGA) infants aimed at TORCH etiologies may incur unnecessary tests and cost.

OBJECTIVE: To determine the frequency of urine CMV PCR and total IgM testing among infants with birth weight <10% and the rate of test positivity. To evaluate the frequency of alternative etiologies of SGA in tested infants.

METHODS: Retrospective chart review of SGA infants admitted to the neonatal intensive care unit (NICU) at NYU Langone Medical Center between 2007 and 2012. Subjects were classified as being SGA with or without intrauterine growth restriction (IUGR). The IUGR subjects were then further categorized as having either symmetric or asymmetric IUGR utilizing the Fenton growth chart at birth. Initial testing for TORCH infections, which included serum total IgM, CMV PCR and head ultrasound, were reviewed and analyzed.

RESULTS: Three hundred and eighty-six (13%) infants from a total of 2953 NICU admissions had a birth weight ≤10th percentile. Of these, 44% were IUGR; 34% being symmetric IUGR and 10% asymmetric. A total of 32% of SGA infants had urine CMV PCR and total IgM tested with no positive results. As expected, significantly higher percentage of symmetric IUGR infants were tested compared to asymmetric IUGR and non-IUGR SGA infants, (64% vs. 47% vs. 19%) P≤0.01. However, 63% of infants with a known cause for IUGR had same testing done aimed at TORCH infections. We calculated additional charges of $64,065 that were incurred by such testing.

CONCLUSIONS: The majority of infants in our study who received testing for urine CMV PCR and total IgM aimed at TORCH infections had one or more other known non-infectious etiologies for IUGR. Because the overall yield of such testing is extremely low, we suggest tests for possible TORCH infections may be limited to symmetric IUGR infants without other known etiologies. Improved guidelines testing for TORCH infections can result in reducing hospital charges and unnecessary studies.