From the Guidelines
If a newborn fails their initial hearing screen, they should undergo one repeat hearing screen before being tested for cytomegalovirus (CMV). This approach is based on the most recent and highest quality study available, which emphasizes the importance of early identification and intervention in cases of hearing loss 1. The repeat hearing screen should ideally be performed before the infant is discharged from the hospital or within the first 2-4 weeks of life.
Rationale for the Recommendation
The rationale behind this recommendation is to balance the need for accurate diagnosis with the importance of timely intervention. Congenital CMV infection is a leading cause of non-genetic hearing loss in children, and antiviral treatment initiated before 1 month of age may prevent further hearing deterioration in affected infants 1. Delaying beyond two failed screens could miss the critical window for diagnosis and intervention.
Key Considerations
- Timing of CMV Testing: CMV testing should be performed as soon as possible after the second failed screen and definitely within the first 21 days of life, as this is the window when congenital CMV infection can be reliably distinguished from postnatal acquisition.
- Method of CMV Testing: Testing for CMV typically involves PCR analysis of urine or saliva samples, with saliva being the preferred sample according to the International Congenital Cytomegalovirus Recommendations Group 1.
- Importance of Early Identification: Early identification of congenital CMV is critical because it allows for the initiation of antiviral treatment before 1 month of age, which may prevent further hearing deterioration in affected infants.
Clinical Practice Guidelines
Clinical practice guidelines, such as those from the American College of Medical Genetics and Genomics (ACMG), support the approach of testing for CMV once newborn hearing loss is confirmed, highlighting the importance of distinguishing between congenital and postnatal CMV infection 1. These guidelines also emphasize the role of other diagnostic tests in evaluating hearing loss, including genetic testing and imaging studies, but CMV testing remains a critical initial step due to its high prevalence as a cause of pediatric hearing loss.
From the Research
Newborn Hearing Screening and CMV Testing
- The exact number of times a newborn's hearing screen should be repeated before screening for Cytomegalovirus (CMV) is not specified in the provided studies 2, 3, 4, 5, 6.
- However, it is recommended that newborns who fail newborn hearing screening should be tested for CMV to ensure appropriate clinical, neurodevelopmental, and audiological follow-up 3.
- A targeted approach that tests neonates who refer on the newborn hearing screen has been implemented in many states and hospital programs, but it fails to identify about 40% of children who experience CMV-related hearing loss 2.
- The studies suggest that CMV testing should be considered after a failed newborn hearing screening, but the optimal number of repeated hearing screens before CMV testing is not clearly defined 3, 4, 5, 6.
CMV Infection and Hearing Loss
- Congenital CMV infection is the leading nongenetic cause of sensorineural hearing loss worldwide 2.
- The majority of infected newborns have no clinical signs of infection, although a substantial proportion may have hearing loss at birth or develop it later in life 2.
- Antiviral treatment with ganciclovir or valganciclovir initiated in the first month of age improves audiologic outcomes 2, 4.
- Valganciclovir-treated children with hearing loss and inapparent cCMV had less hearing deterioration at 18 through 22 months of age than control subjects 4.