INTRODUCTION — Significant permanent hearing loss is a common disorder at birth and can lead to delayed language development, difficulties with behavior and psychosocial interactions, and poor academic achievement. Detection of hearing loss during infancy can initiate intervention resulting in improved language, cognitive, behavioral, and academic outcomes.

Screening for hearing loss in the newborn will be reviewed here. The etiology, evaluation, and management of hearing impairment in children are discussed separately. (See "Hearing loss in children: Etiology" and "Hearing loss in children: Screening and evaluation" and "Hearing loss in children: Treatment".)

DEFINITION

Severity of hearing loss — The extent of hearing loss is defined by measuring the hearing threshold in decibels (dB) at various frequencies. Normal hearing has a threshold of -10 to 15 dB. Hearing loss ranges from slight to profound. In individuals with bilateral hearing loss, the severity of loss is based on the better-functioning ear. Severity of hearing loss defined by the American Speech-Language Hearing Association as follows [1-3]:

●No hearing loss – -10 to 15 dB

●Slight – 16 to 25 dB

●Mild – 26 to 40 dB

●Moderate – 41 to 55 dB

●Moderately severe – 56 to 70 dB

●Severe – 71 to 90 dB, or 61 to 80 dB based on the World Health Organization (WHO) definition [2]

●Profound – >91 dB, or >80 dB based on WHO definition

CLASSIFICATION — Neonatal hearing loss can result from transient or permanent conductive, permanent sensorineural, auditory neuropathy, and mixed defects (table 1) (see "Hearing loss in children: Etiology"):

●Conductive loss is caused by abnormalities of the outer or middle ear, which limits the amount of external sound that gains access to the inner ear (cochlea and vestibular apparatus). Cochlear function remains normal because the inner ear develops separately from the external and middle ears. Conductive hearing loss may be either transient (middle ear fluid) or permanent (anatomical). Transient conductive hearing loss is a frequent cause of a false-positive neonatal screen [4].

●Sensorineural hearing loss (SNHL) results from malfunction of inner ear structures, including the outer and inner hair cells of the cochlea and the eighth cranial nerve components of the auditory neural pathway.

●Auditory neuropathy (AN) is a hearing disorder that affects the neural processing of auditory stimuli and may involve the eighth cranial nerve, auditory brain stem, or cerebral cortex. Sound enters the inner ear (cochlea and outer hair cells) normally, but the transmission of signals from the inner hair cells of the cochlea to the auditory nerve/pathway is either absent or severely distorted. Screening for hearing loss using otoacoustic emissions will not detect patients with AN, as their outer hair cells function normally. (See 'Comparison of AABR and OAE' below.)

●Mixed hearing loss occurs when there is a conductive component in combination with SNHL or AN. There is impairment in the middle ear and inner ear or auditory nerve.

EPIDEMIOLOGY

General neonatal population — Significant bilateral hearing loss is the most common congenital disorder at birth, occurring in 2 to 3 per 1000 newborns [5,6]. In the United States, data from the Centers for Disease Control and Prevention (CDC) (2019 CDC Early Hearing Detection and Identification) reported a rate of permanent hearing loss of 1.7 per 1000 infants screened for hearing loss, with an overall screening rate of 98.4 percent for all newborns, excluding infant deaths and parental refusal. There was no documented diagnosis reported in 38.0 percent of infants who failed the newborn hearing screening.

The prevalence of moderate, severe, and profound bilateral permanent hearing loss is estimated at 1 in 900 to 2500 newborns [7,8]. The prevalence of unilateral hearing impairment above 30 decibels (dB) has been reported as 6 out of 1000 newborns [2].

The causes of hearing loss remain unidentified in one-quarter to one-half of infants and children with permanent hearing loss [9,10]. For patients with a confirmed diagnosis, hearing loss may be due to genetic/hereditary disorders or acquired conditions due to perinatal problems (eg, congenital viral infections) [6]. Permanent hearing loss is often associated with other abnormalities, and there are over 400 syndromes reported to be associated with permanent hearing loss (table 2). (See "Hearing loss in children: Etiology".)

NICU patients — Infants cared for in a neonatal intensive care unit (NICU), which includes neonatal level II, III, and IV care units, are at greater risk of hearing loss compared with healthy term infants [11-13]. In particular, sensorineural hearing loss (SNHL) and auditory neuropathy (AN) are much more common with reported rates of SNHL and AN of 16.7 and 5.6 per 1000 infants cared for in a NICU compared with an estimated incidence in a well-baby population of 0.06 per 1000 infants [11,12]. If infants with hyperbilirubinemia are included in the well-baby population, the incidence rises to 0.3 per 1000 infants, still one-tenth of the rate seen in infants cared for in the NICU.

Risk factors associated with acquired hearing loss due to SNHL and AN include congenital infections, severe hyperbilirubinemia, which may require phototherapy, and in rare cases, exchange transfusion and admission to a neonatal intensive care unit (NICU) (table 3) [8].

RATIONALE FOR SCREENING — Screening newborns for hearing loss leads to earlier detection and intervention in patients with congenital hearing impairment. Early intervention can significantly improve language acquisition and educational achievement in affected patients [1,14-19].

Earlier detection — The evidence is clear that screening newborns detects hearing loss at a significantly earlier age than relying solely on identifying clinical signs of hearing loss [20-24]. Caregivers and clinicians are not able to detect hearing loss in infants until there is recognition of delayed speech and language milestones.

This point was best illustrated by a controlled trial of 53,781 neonates born in four English hospitals from 1993 to 1996 that alternated periods of time between universal newborn hearing screening (UNHS) and no screening [20]. Overall, 106 cases of bilateral permanent hearing impairment per 100,000 target population were identified. After adjustment for severity of hearing loss, infants with hearing loss born during periods of screening compared with those born during periods without screening were more likely to be detected at an earlier age (odds ratio [OR] 5, 95% CI 1-23) and receive earlier intervention (OR 8, 95% CI 1.5-41). In a follow-up study, the proportion of seven- to nine-year-old children with permanent hearing impairment who were identified before six months of age was higher during periods of UNHS compared with periods of no screening (74 versus 31 percent) [25].

Earlier diagnosis improves outcome — Based on several controlled studies of long-term outcome, the evidence supports that earlier diagnosis and intervention for permanent hearing loss in infants can improve language and developmental outcome [1,15-19,26]. Earlier diagnosis allows for earlier introduction of hearing aids.

The beneficial effect of early detection and intervention on language development was demonstrated in follow-up studies of the 120 children with bilateral permanent hearing loss from the birth cohort of the previously mentioned trial comparing UNHS with no screening. Children whose permanent hearing loss was confirmed by nine months of age compared with those with confirmation after nine months of age had better receptive and general language abilities [15,16,20,25]. In subsequent follow-up reports, patients from this cohort who were identified before nine months had better reading and communication skills than those diagnosed after nine months of age through adolescence [15,17].

SCREENING TESTS FOR HEARING — The American Academy of Pediatrics (AAP) Task Force on Newborn and Infant Hearing defined an effective neonatal hearing screening test as one that detects hearing loss of ≥35 decibels (dB) in the better ear and is reliable in infants ≤3 months of age [27].

Two electrophysiologic techniques meet these criteria:

●Automated auditory brainstem responses (AABR)

●Otoacoustic emissions (OAE)

Both AABR and OAE techniques are inexpensive, portable, reproducible, and automated. They evaluate the peripheral auditory system and the cochlea, but cannot assess activity in the highest levels of the central auditory system. These tests alone are not sufficient to diagnose hearing loss; thus, any child who fails one of these screening tests requires further audiologic evaluation. In addition, both methods will miss mild hearing loss. (See 'Infants who fail two-stage screening' below and "Hearing loss in children: Screening and evaluation".)

Automated auditory brainstem response — AABR measures the summation of action potentials from the eighth cranial nerve (cochlear nerve) to the inferior colliculus of the midbrain in response to a click stimulus. It can detect both sensorineural hearing loss (SNHL) and auditory neuropathy (AN). Other names for this test include the screening ABR (SABR), and screening brainstem auditory evoked response (BAER). Approximately 4 percent of infants screened with AABR are referred for further audiologic evaluation, which uses a diagnostic ABR including an evaluation by an audiologist skilled in assessing infants and young children [27].

It is important to note the difference between AABR and ABR, as AABR is a screening tool with an automated pass/fail response whereas an ABR diagnostic test provides quantitative data (eg, waveforms) that must be interpreted by a trained audiologist, thereby determining the degree and the site of the hearing loss. As an example, delayed or absent waves suggest a neurologic or cochlear deficit. Many neonatal intensive care units (NICUs) now complete the diagnostic ABR prior to discharge for infants who fail the screening AABR.

Technique — The AABR utilizes click or chirp stimuli presented at 35 dB. Three surface electrodes placed on the forehead, nape, and mastoid or shoulder detect waveform recordings generated by the ABR to the stimuli. In the screening AABR, the morphology and latency of the waveforms are compared with normal neonatal templates, and a pass or fail reading is generated, and the examiner does not need to interpret the waveforms if visibly accessible. AABR screening typically requires 4 to 15 minutes for testing, although newer AABR screening equipment can complete testing in an infant in 4 to 8 minutes in ideal conditions.

Otoacoustic emissions — OAE testing measures the presence or absence of sound waves (ie, OAEs) generated by the cochlear outer hair cells of the inner ear in response to sound stimuli. A microphone at the external ear canal detects these low-intensity OAEs. Since OAE evaluates hearing from the middle ear to the outer hair cells of the inner ear, it is used to screen for SNHL but cannot detect AN.

Technique — The apparatus for OAE screening consists of a miniature microphone placed into the infant's outer ear canal. The microphone produces a stimulus (clicks or tones) and detects sound waves as they arise from the cochlea. The device also measures the signal-to-noise ratio to ensure accuracy. OAE screening generally requires approximately one to two minutes per ear in ideal testing conditions.

Tests most commonly used for clinical purposes are transient OAEs (TOAEs) and distortion product OAEs (DPOAEs). They are classified by the stimuli used to produce the cochlear basal membrane vibrations.

Comparison of AABR and OAE — The following is a comparison between the automated auditory brainstem response (AABR) and otoacoustic emissions (OAE) screening methods:

●Test time – OAE tends to require less patient preparation time and a shorter test time than AABR [28]. AABR may also present time constraints because infants need to be asleep or quiet awake when tested. In contrast, OAE can be performed when the infant is awake, feeding, or sucking on a pacifier [29]. Response time, however, is much quicker for OAE if the infant is sleeping or quiet awake.

●Interference – OAE is sensitive to background noise, and physiological noise generated by the baby [30]. It may be difficult to obtain OAE responses at low frequencies due to physiological noise, myogenic noise, or poor acoustics. This noise interference is greater when the recorded frequency is below 1500 Hertz (Hz). Thus, screening with OAE can be improved by programming protocol parameters to include select high frequencies, which are more important for understanding speech [30-32]. These protocol changes should be implemented by an audiologist with a specialized skill set in pediatrics. OAE, unlike AABR, is not subject to muscle artifact [29,33]. AABR can also be complicated by electrical artifacts [29].

●False-positive results – During the first three days of life, there is an increased false-positive rate with OAE compared with AABR, most commonly due to transient conductive hearing loss caused by vernix occluding the external ear canal or middle ear fluid (due to amniotic fluid). [33-36]. In several reports, 19 to 25 percent of newborns with abnormal OAE screening during the first three days after birth had subsequent normal hearing in follow-up testing [35-38]. In one study, cleaning of vernix increased the pass rates from 59 to 69 percent [36].

It is important to recognize that the pass threshold is higher for OAE than for AABR, resulting in a higher fail rate. Both methods will miss minimal and mild hearing loss.

●Tympanic membrane mobility – OAE requires normal middle ear function. Thus, decreased tympanic membrane mobility can reduce screening pass rates with this technique [29]. The magnitude of this problem was illustrated in a series of 200 infants, in which the pass rate in the 23 percent of infants with decreased tympanic membrane mobility was lower with OAE than AABR (33 versus 95 percent, respectively) [36]. This issue is not currently assessed in screening programs in the United States.

●Auditory neuropathy – Infants at risk for developing AN include those with severe hyperbilirubinemia, prematurity, perinatal asphyxia, craniofacial abnormalities, and others who are admitted to neonatal intensive care units (NICUs). AABR will detect the hearing loss in infants with AN, but OAE will not. Therefore screening for AN with OAE may lead to a false-negative result [29,39]. Thus, AABR should always be used to screen hearing in infants who are at risk for AN (eg, infants with hypoxia, prematurity, hyperbilirubinemia, neurologic impairment and all infants who require ≥5 days of NICU care).

●Relative costs – Although the actual screening cost is lower for OAE compared with AABR, the overall cost of screening and audiologic evaluation may be lower with AABR because of the lower referral rate for diagnostic audiologic assessment, although this varies by location. One study evaluated screening programs initiated at two sites, one using automated ABR administered by neonatal nurses and the other using OAE performed by master's level audiologists [40]. Less time was needed for testing with OAE than with AABR (5 versus 13 minutes), but the rate of referral for further testing was higher with OAE (15 versus 4 percent). Although the costs before discharge were similar for the two programs, the increased referral rate with OAE increased the overall cost per infant screened.

RISK FACTORS FOR HEARING LOSS — Major risk factors for neonatal hearing loss includes the following (table 3) [7,41]:

●Neonatal intensive care unit (NICU) admission for at least five days.

●Syndromes associated with hearing loss (table 2).

●Family history of hereditary childhood hearing loss.

●Craniofacial anomalies (eg, anomalies of the pinna or ear canal, cleft lip, and palate).

●Congenital infection (eg, cytomegalovirus, toxoplasmosis, rubella, syphilis, herpes, Zika) or bacterial meningitis.

●Severe hyperbilirubinemia defined as serum bilirubin >35 mg/dL (599 micro/L) or requiring exchange transfusion in a preterm infant [42].

●Delivery complications including perinatal asphyxia, cooling, or problems during delivery (eg, five-minute Apgar score <6).

●Multiple courses of ototoxic mediation (ie, ampicillin, gentamycin, oxacillin, tobramycin).

Approximately 10 to 30 percent of newborns have one or more of these risk factors. An infant's risk of having a permanent hearing loss rises as the number of risk factors increases [41]. Of note, many of the same risk factors (congenital infection, hyperbilirubinemia, perinatal asphyxia) are associated with both sensorineural hearing loss (SNHL) and auditory neuropathy (AN). In contrast, craniofacial abnormalities, are most often associated with permanent conductive loss due to abnormalities of the pinna, including microtia and atresia of the ear canal. As a result, a comprehensive diagnostic audiology assessment by an audiologist skilled in assessing young infants and children is required to guarantee the most optimal evaluation and treatment including amplification for the infant.

NICU admissions — Because of the increased risk for SNHL and AN, hearing loss should be screened by automated auditory brainstem response (AABR) for all patients cared for in a NICU for >5 days since otoacoustic emissions (OAE) screening will fail to detect AN, as recommended by the Joint Committee on Infant Hearing (JCIH) [27,39].

Infants admitted to the NICU have a 2 percent risk for hearing loss, primarily due to SNHL and AN [11,43]. Preterm infants, especially very low birth weight (VLBW) infants, (BW <1500 g) are at increased risk for SNHL and AN. The risk of hearing loss increases with decreasing BW and for VLBW infants is six times more common than for those with normal BW [43].

SELECTIVE SCREENING — Prior to universal newborn hearing screening (UNHS), one approach to identifying infants with a permanent hearing loss was to selectively test newborns that are at increased risk for hearing loss (table 3). There is strong evidence that this approach will miss and delay detection of hearing loss in a significant number of patients and is no longer recommended. Universal screening for all newborn infants is supported by global health care organizations, professional societies, and the United States Preventive Services Task Force (USPSTF) [14]. (See 'Rationale for screening' above and 'Universal screening' below.)

A targeted screening program using the risk factors discussed above can identify only 50 to 75 percent of infants with moderate to profound bilateral hearing loss [7,44], and the time of diagnosis may be delayed [45]. In addition, selective screening alone delays the detection of hearing loss in a substantial number of children with congenital hearing loss who do not have any identifiable risk factors [7,21,34,46-50]. Therefore, targeted screening is not recommended.

UNIVERSAL SCREENING — Universal newborn hearing screening (UNHS) is the preferred method to screen newborns for hearing loss [14,27,51].

Goal of newborn screening — The goal of UNHS is early recognition and treatment of hearing loss, thereby maximizing linguistic competence and literary development of children who are deaf or hard of hearing [27,52]. With the widespread adoption of UNHS, the age at identification of hearing loss has decreased from a range of 24 to 30 months to 2 to 3 months of age [53].

In the United States, the impact of UNHS has been shown by the Centers for Disease Control and Prevention (CDC) Early Hearing Detection and Intervention Programs [5,54].

●Reported data from the 2019 CDC Early Hearing Detection and Identification from 47 states and 7 territories showed 98 percent of births (3.5 million infants, excluding refusals, were screened, of which 1.7 percent infants (n = 61,475) did not pass the final newborn screen [5].

●In the group that did not pass UNHS, 9.7 percent of infants (n = 5934) were diagnosed as permanent hearing loss for a prevalence of 1.7/1000,52.4 (n = 32,193) percent were diagnosed with normal hearing. 37.9 percent (n = 23,374) had no documented diagnosis (which included infants lost to follow-up, with loss of documentation or in the process of evaluation at the time of reporting, or those with parental/caregiver refusal for evaluation).

●Two-thirds of the infants diagnosed with hearing loss were actively enrolled in early intervention.

Guidelines — Guidelines supporting universal screening include the following:

●The United States Preventive Services Task Force (USPSTF) recommended UNHS based upon its review of the evidence that demonstrated available inexpensive screening tests can accurately identify newborns with permanent hearing loss, and early detection improves language outcomes [14,51].

●The Joint Committee on Infant Hearing (JCIH) recommends implementing an integrated, interdisciplinary system of UNHS to detect and treat early hearing loss [27].

These guidelines include the following Early Hearing Detection and Intervention (EHDI) 1-3-6 recommendations [14,27]:

●All newborns should be screened before they reach one month of age. Either otoacoustic emissions (OAE) or automated auditory brainstem response (AABR) can be used in a single-stage or two-stage UNHS protocol. (See 'Protocols' below.)

●Audiologic assessment of all infants who fail their screening test by three months of age. (See 'Infants who fail two-stage screening' below and "Hearing loss in children: Screening and evaluation".)

●Intervention for those infants with significant hearing impairment by six months of age designed to meet the individualized needs of the infant and family/caregiver [55,56]. (See "Hearing loss in children: Treatment".)

Program attributes — A screening program with a medical director and adequate trained staff should be established at each birth hospital. Attributes of an effective screening program include [27,57]:

●Screening a minimum of 95 percent of infants before hospital discharge. Either OAE or AABR can be used for normal term infants, but for infants at risk for auditory neuropathy (AN) (eg, infants admitted to the neonatal intensive care unit [NICU]), AABR should be used. (See 'NICU admissions' above and 'Comparison of AABR and OAE' above.)

●A false-positive rate (infants with a positive screening test who do not have hearing loss) ≤3 percent and a rate of referral for audiologic testing after a positive screening result ≤4 percent.

●A false-negative rate (infants with significant hearing loss who are missed by the screening test) of zero.

●A follow-up rate of infants referred for audiologic assessment and for infants who were not screened in their birthing hospital (whose parents did not refuse screening) of at least 95 percent.

●Rescreening for infants who are readmitted within the first month of life for conditions associated with potential hearing loss (eg, hyperbilirubinemia and meningitis).

●An effective communication system that ensures results of screening tests from the birth hospital are conveyed to the family/caregiver and the designated primary care provider, and referral of infants who fail the screening test for audiologic assessment.

Protocols — The two types of universal screening protocols routinely used are single- or two-stage UNHS.

Single stage — A single-stage UNHS utilizes one screening test, either OAE or AABR, which detects 80 to 95 percent of ears with hearing impairment. With either single test, there is a high false-positive rate resulting in a substantial number of infants with normal hearing referred for audiologic assessment, thereby increasing the overall cost of UNHS. Referral for audiologic evaluation is generally required for 4 percent of infants screened with AABR [58,59] and between 5 to 21 percent of infants screened with OAE [23,46]. The prevalence of moderate to severe hearing loss is estimated to be one case for every 900 to 2500 newborn infants. Thus, for one case of significant hearing loss, the number of infants with normal hearing referred for audiologic evaluation after a single-stage screen would range from 40 to 500 patients. As a result, the majority of United States hospitals now have a two-stage neonatal hearing screen protocol.

Two stage — In a two-stage screening protocol, a second screen is given to patients who fail the initial study, and only patients who fail both screens are referred for audiologic assessment (algorithm 1 and algorithm 2) [60]. The two-stage protocol is preferred as it reduces the rate of false-positive tests and reduces the referral rate for audiologic assessment [61,62].

Data from studies utilizing a two-stage UNHS reported that approximately 900 to 1400 infants would need to be screened to identify one case of bilateral hearing loss [20,63]. It is estimated that one of every 45 infants from the well-baby nursery referred for audiologic evaluation by a two-stage UNHS would have moderate to profound bilateral permanent hearing loss [7].

However, the two-stage screening may miss infants with hearing loss, because it inaccurately assumes that all infants who fail the initial screen but pass the second have normal hearing [60,64,65]. In addition, the screening devices currently available have thresholds of approximately 35 decibels (dB) and will miss mild hearing loss, which will delay diagnosis of hearing loss. Because of this finding, continued surveillance of hearing skills and language development as described in the AAP periodicity schedule is recommended by the JCIH and AAP.

APPROACH TO BIRTH HOSPITALIZATION SCREENING

Well-baby nursery — In the well-baby nursery setting (neonatal level of care 1), we suggest performing two-stage UNHS primarily to reduce the number of infants with normal hearing who would be referred for further audiologic assessment (algorithm 1) (see 'Two stage' above). Infants are screened initially with OAE, and those who fail the OAE are then screened using either OAE or AABR.

OAE is the preferred initial test because of the following [66]:

●OAE takes less time to administer.

●OAE is less costly to administer.

●OAE can be administered to the awake infant, which is not the case for AABR, which is best done with an infant quiet awake or asleep.

●Incidence of auditory neuropathy (AN), which would not be detected by OAE, is low in infants admitted to the well-baby nursery.

If an infant fails both screens, we suggest that the patient be referred to an audiologist who is skilled in assessing infants for hearing loss prior to discharge to home. If evaluation by a skilled pediatric audiologist is not possible, the infant can be rescreened after they are discharged, but follow-up should be no later than three months of age. (See 'Infants who fail two-stage screening' below.)

Infants in the well-baby nursery who pass the newborn screen but have a risk factor for hearing loss should be closely monitored and referred for further audiology assessment depending on the pathogenesis of the disorder and parent or provider concerns. Each infant should have at least one assessment by 9 months of age [27]. (See 'Other at-risk patients who passed initial screening' below.)

If a program decides to utilize only a one-stage UNHS, screening with AABR is recommended as it results in a lower false-positive rate and lower referral rate for audiologic assessment than OAE, and can detect infants with AN [39,67]. (See 'Comparison of AABR and OAE' above.)

Information for parents should be provided on the importance of screening the newborn for hearing loss and the need for follow-up for infants who fail screening. Many states have legislation specifying language requirements of readily available education/information materials of newborn hearing screening for major languages in the state, which are identified in the state statute.

NICU — For infants admitted to the neonatal intensive care unit (NICU), AABR is the initial test recommended due to the increased risk of AN in this population (algorithm 2). This approach concurs with the guidelines of the Joint Committee on Infant Hearing (JCIH) [27]. (See 'NICU admissions' above.)

FOLLOW-UP — For all infants regardless of the results of the screening test, continued surveillance by the primary care provider for hearing problems is recommended and includes assessment of developmental milestones, speech, auditory skills, parental concerns, and middle ear status during routine well-child visits [27,68]. Additional recommendations for follow-up are based on the clinical setting. Rescreening for hearing loss can be performed in the outpatient setting or in the medical home [51,69].

Infants who fail two-stage screening

Audiologic assessment and management — (See "Hearing loss in children: Screening and evaluation", section on 'Formal audiology'.)

●Well-baby nursery ‒If an infant has failed the two-stage newborn hearing screening test, audiologic assessment should be performed preferably before birth hospitalization discharge (algorithm 1 and algorithm 2). If audiologic assessment is not available before discharge, referral to an audiologist skilled in evaluating infants for hearing loss should be done as soon as possible and no later than three months of age [14,27].

●NICU ‒ For infants cared for in the neonatal intensive care unit (NICU), audiology testing should be performed for infants who failed screening prior to discharge as they are at-risk for hearing loss [14,27].

Subsequent management of hearing issues should be done by a multidisciplinary team that is skilled in caring for infants and children with hearing loss that includes audiologists, otolaryngologists, speech pathologists, geneticists, and educational specialists.  

Screening for cytomegalovirus — Targeted screening for cytomegalovirus (CMV) has been suggested for all newborn infants who fail newborn hearing screening. This approach is based on the knowledge that CMV is the most common infectious cause of permanent neonatal or late onset hearing loss and there is a potential that antiviral therapy given within the first month of life may improve outcome. However, data are limited on the benefits of screening for CMV in all infants who fail the newborn hearing screening outweigh the burden, cost and potential adverse effects of follow-up and therapy [70].

In our practice, until further evidence is available, targeted screening for CMV is recommended for infants who fail the hearing test who have symptoms consistent with congenital CMV, and/or who are cared for in the NICU, as this subpopulation has a higher risk of CMV [71]. However, other centers provide targeted CMV screening for infants who fail the newborn hearing screen. We prefer polymerase chain reaction testing of urine samples versus saliva, as the former is a more accurate screening test [72,73]. (See "Congenital cytomegalovirus infection: Clinical features and diagnosis", section on 'Approach to testing'.)

If screening is performed and is positive for CMV, diagnostic studies confirming CMV infection are sent. Treatment may be initiated after the family/caregivers are informed by the management team of the risks and benefits of antiviral therapy. (See "Congenital cytomegalovirus infection: Clinical features and diagnosis", section on 'Diagnostic approach' and "Congenital cytomegalovirus infection: Management and outcome", section on 'Whom to treat'.)

Alternatively, the medical team can present options to the family/caregivers regarding CMV screening and the risks and benefits of treating infants with only isolated hearing loss, so that the family/caregivers can make an informed decision regarding CMV screening.

The efficacy of neonatal CMV screening remains controversial [74]. Available data regarding CMV screening for infants who fail hearing screening demonstrate that targeted screening will miss a majority of neonates with congenital CMV [74,75].

●In a multicenter study of newborn infants (n = 99,945), universal screening was performed for both hearing and CMV [75]. Overall, the rate of congenital CMV was 0.4 percent. The rate of failing the hearing screen was higher in the CMV-positive group compared with those who were CMV-negative (7 versus 1 percent). Two-thirds of infants with CMV who failed their hearing screening were diagnosed with SNHL. However, in asymptomatic CMV positive infants, newborn screening identified 9 of 19 infants who had hearing loss, thereby missing almost half of the patients with hearing loss. As a result this targeted approach did not identify 43 percent of infants with CMV-related hearing loss due in part to progressive and late-onset hearing loss in patients with asymptomatic CMV.

●In a state-wide study that utilized data from the Utah Department of Health, of the 509 infants who failed hearing screening, 234 were screened for congenital CMV (screened within 21 days of age) [71]. Fourteen of these infants were diagnosed with congenital CMV, and six had hearing loss. An additional 80 patients were screened after 21 days of age for CMV, and of the seven who tested positive for CMV, three had hearing loss. However, an accompanying editorial points out there were an estimated 400 to 700 infants with congenital CMV during the same study period, most of whom were not detected by these data [74].

In addition, diagnosis of congenital CMV depends on sending a urine or saliva sample for viral culture by 21 days of age. Finally, there are no data on the outcome of antiviral therapy for infants with congenital CMV and only isolated hearing loss.

Nevertheless, as of 2017, four states (Connecticut, Iowa, Utah, and Illinois) have passed legislation requiring or offering neonatal CMV testing for all infants who fail the newborn hearing screen. However, we believe additional longitudinal population-based studies are needed to study the long term efficacy of universal and targeted screening for CMV, the effect of antiviral therapy including adverse effects, and the overall cost effectiveness of CMV screening. Although survivors of symptomatic congenital CMV are at greater risk of adverse outcomes, including hearing loss, than survivors of asymptomatic CMV, long-term follow-up and management are needed for both groups of children [76,77].

Until additional information is available, we continue to provide targeted CMV screening for infants with a diagnosis of hearing loss with neurologic findings consistent with a diagnosis of congenital CMV infection or who were cared for in the NICU. Treatment may be initiated after the family/caregivers is fully informed by the management team regarding the risks and benefits of antiviral therapy and all questions are answered.

Term infants who failed initial screen but passed the second — The primary care providers should provide increased oversight for term infants who fail the initial screen but pass the second screening test, as they are still at risk for hearing loss. If any clinical suspicion arises regarding the patient's hearing, a referral to an audiologist skilled in evaluating children and an auditory brainstem response (ABR) or visual reinforcement audiometry (VRA) based on the age of the infant should be performed [2].

Infants who pass initial screening — Follow-up for infants who pass the initial screening includes continued routine monitoring of language acquisition, auditory skills, middle ear status, and attention to parental concerns, if they should arise. Additional oversight and testing are reserved for term infants who failed OAE but passed AABR, NICU graduates, and infants with risk factors for hearing loss who passed newborn screening.

NICU graduates — Infants cared for in the NICU who pass the two-stage initial screening test but have known risk factors for hearing loss are at increased risk of late-onset hearing loss. If there are parental/caregiver concerns, at-risk NICU graduates should be referred to an audiologist for follow-up assessment. Testing should be done by visual reinforcement audiometry (VRA). (See 'Test choices' below and "Hearing loss in children: Screening and evaluation", section on 'Tests for young and/or uncooperative children'.)

Because of the risk of hearing loss, the Joint Committee on Infant Hearing (JCIH) recommends one audiologic reassessment by 9 months for any infant who passed the neonatal screen and required more than five days of NICU care or has one or more of the following risk factors regardless of length of the NICU stay [27]:

●Received extracorporeal membrane oxygenation (ECMO) therapy

●Received mechanical ventilation

●Exposed to nephrotoxic drugs, such as aminoglycosides (eg, tobramycin and gentamicin) and loop diuretics (eg, furosemide)

●Hyperbilirubinemia that required exchange transfusion

In addition, very low birth weight (VLBW) preterm infants (BW <1500 g) are at risk of experiencing progressive or delayed-onset hearing loss. As a result, these infants should have follow-up monitoring with a diagnostic hearing test by 9 months adjusted age [27,68,78].

In our state early detection program, the Rhode Island Early Hearing Detection and Intervention (EHDI) program, assessment is performed at an earlier age between 7 and 12 months of post-menstrual age (PMA) so intervention can be provided as early as possible for identified early loss.

Other at-risk patients who passed initial screening — Universal newborn hearing screening (UNHS) does not identify all cases of pediatric hearing loss since hearing loss can evolve after the newborn period (eg, meningitis, head trauma, ototoxic medications), and there also remain cases that were not detected by UNHS (ie, false-negative rates) [79-82]. In addition, some types of genetic disorders or infections (cytomegalovirus [CMV] and Zika virus) may have a delayed onset [83]. As a result, the JCIH recommends audiologic reassessment by 9 months of age for any infant with the following [27]:

●Family history of permanent childhood hearing loss.

●Congenital infections such as cytomegalovirus (CMV), herpes simplex virus, rubella, syphilis, Zika virus [84], and toxoplasmosis. In these infants, assessment is performed between 1 and 3 months of age. (See "Overview of TORCH infections".)

●Craniofacial anomalies, that involve the pinna, ear canal (including microtia and atresia), cleft lip, cleft palate, and temporal bone anomalies.

●Syndromes associated with deafness, including Waardenburg syndrome. (See "The genodermatoses: An overview", section on 'Waardenburg syndrome'.).

●Culture-positive postnatal infections (eg, bacterial and viral meningitis) are associated with subsequent sensorineural hearing loss (SNHL) or auditory neuropathy (AN). (See "Bacterial meningitis in the neonate: Clinical features and diagnosis".)

Earlier and repeated assessments may be indicated for children with CMV infection, genetic conditions associated with progressive hearing loss, some neurodegenerative disorders, culture-positive postnatal infections associated with SNHL, or when concerns are raised regarding hearing skills or speech development by the parent or primary care provider [27].

Test choices — VRA is the gold standard for hearing assessment for nonverbal children [85]. However, VRA cannot be performed reliably before the infant is six to nine months of developmental age [86]. Until VRA can be performed, infants who fail a screening test should have a diagnostic ABR performed, which includes testing with click stimuli, tone burst stimuli, or chirp stimuli from loud (80 to 90 decibels [dB]) to soft (0 to 20 dB). The audiological evaluation of infants is discussed in greater detail separately. (See "Hearing loss in children: Screening and evaluation", section on 'Tests for young and/or uncooperative children'.)

Treatment: Hearing aids and assistive devices — For children with documented hearing loss, hearing amplification can be provided with hearing aids, cochlear implants, and other assistive listening devices, which are discussed separately. In addition, educational and psychological support should be provided to all children with hearing loss and their families/caregivers. In Rhode Island, families/caregivers are referred to the Hands and Voices, a parent-driven, nonprofit organization dedicated to providing unbiased support to families/caregivers with children who are deaf or hard of hearing. (See "Hearing loss in children: Treatment".)

LOST TO FOLLOW-UP — The success of a universal newborn hearing screening (UNHS) program is dependent upon ensuring that every infant who fails the initial screening test be assessed by audiologic evaluation by three months of age [27]. Infants with significant hearing loss can be missed if they cannot be located due to inadequate tracking procedures [40].

In the United States, despite the almost universal compliance with initial UNHS, the losses to follow-up and failure to document have remained problematic. About one-third of infants who fail the newborn screening test are lost to follow-up [87-90]. Reasons for failure of follow-up were family/caregivers unresponsiveness, inability to contact, or unknown. In addition, new challenges for screening and follow-up occurred with the onset of the COVID pandemic in March 2020.

Barriers to adequate follow-up include [91]:

●Insufficient support system to track patients with a positive screening test

●Primary care provider lack of knowledge regarding screening test results

●Challenges to families/caregivers in obtaining services

●Insufficient number of audiologists to perform further evaluation

●Poor socioeconomic status [92-94]

Targeting these challenges, especially for at-risk groups, may improve return rates for further audiologic evaluation. For example, in Massachusetts and Colorado, the UNHS programs actively follow-up with families/caregivers and providers, resulting in a lost to follow-up rate of only approximately 6 percent. Participation of other programs or services can also be used to effectively target follow-up [95].

Nevertheless, in the United States, the overall lost to follow-up rate of 27.5 percent for newborn screen referrals in 2019 remains unacceptable [96,97]. Improved state early hearing detection and identification program tracking procedures and follow-up with families/caregivers by their primary care providers are needed as discussed below.

Tracking — Establishment of a statewide data management system is critical for tracking and ongoing surveillance of infants who fail the newborn screen or have a risk factor for hearing loss, and facilitating communication with providers. In the United States, all states have an Early Hearing Detection and Intervention (EHDI) coordinator who is available to assist providers. Another resource available to providers in the United States is the EHDI-PALS website, which provides information on audiology facilities that provide pediatric services.

In Rhode Island, which is where the author practices, newborn hearing screening results are provided to the family/caregivers prior to discharge, a letter is sent to the primary care provider, and the data are entered into a state database, KIDSNET (located in the state's Department of Health). This data system links births, birth defects, and information from the Rhode Island Hearing Assessment Program (RIHAP) from birthing hospitals, audiologists, and pediatricians. RIHAP provides primary care physicians with regular lists of patients needing audiology follow-up (figure 1). The RIHAP working group also includes a parent of a child with deafness, who plays a key role for liaison and support for parents/caregivers with a newly diagnosed deaf or hard of hearing child. In addition, the parent member reviews all the resources and opportunities including referral to early intervention programs for children who are deaf and hard of hearing.

SCREENING IN THE UNITED STATES

Cost — The cost of universal newborn hearing loss (UNHS) in statewide programs ranges from USD $10 to $50 per infant screened. A higher rate of referral for audiologic assessment will increase the cost. This rate is comparable to that for metabolic screening, although the incidence of hearing impairment is higher. The cost of identifying one affected child is approximately USD $4000 to $22,000 for hearing loss, compared with $10,000 for phenylketonuria and $40,000 for hypothyroidism [98]. Additional cost savings may accrue if UNHS results in fewer children who require special education and fewer adults with resultant disability [53].

Implementation — By 2007, all the states in the United States had implemented newborn screening programs for hearing loss. In addition, universal newborn and infant hearing screening laws have been passed in the majority of states, Guam, and the District of Columbia. Practitioners should know whether UNHS is mandated in their state, including any specific legal requirements. Information for each state is available at the National Center for Hearing Assessment and Management.

As a result of these efforts, 98.4 percent of infants born in the United States were screened for hearing loss and 97.7 percent were screened before one month of age in 2019 [97]. Almost 85 percent of newborns diagnosed with permanent hearing loss were referred to early intervention, 67 percent enrolled in early intervention, with almost 100 percent enrolled before six months of age.

In addition, a 10-year quality assurance review of the two-stage screening program for Dutch neonatal intensive care unit (NICU) graduates demonstrated 96 percent of NICU patients were screened before one month of corrected gestational age, and 82 percent were tested before six weeks of age [99]. Two-thirds of the patients with hearing loss were diagnosed before three months of age.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Hearing impairment in infants and children".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topic (see "Patient education: Screening for hearing loss in newborns (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Epidemiology ‒ Significant hearing loss occurs in 1 to 3 newborns per 1000 live births. Infants cared for in neonatal level of 2 and 3 care units (neonatal intensive care units [NICU]) are at-risk for sensorineural hearing loss (SNHL) and auditory neuropathy (AN). (See 'Epidemiology' above.)

●Rationale for screening ‒ Newborn screening detects hearing loss at an earlier age, resulting in earlier intervention (eg, use of hearing devices and access to language [speech or sign]). Earlier detection and intervention improves language and reading development. (See 'Rationale for screening' above.)

●Screening tests ‒ Two electrophysiologic techniques, automated auditory brainstem responses (AABR) and otoacoustic emissions (OAE), are routinely used as screening tests. Both tests are portable, automated, and inexpensive, making them well suited to newborn screening. However, OAE does not detect AN, and AABR should be used to screen infants who are at risk for AN. (See 'Screening tests for hearing' above and 'NICU admissions' above.)

●Universal screening ‒ Universal screening for hearing loss is preferred because targeted selective screening for only at-risk infants would fail to identify 50 to 75 percent of all cases of moderate to profound bilateral hearing loss. As a result, the diagnosis of hearing loss would be delayed in a substantial number of affected neonates with only selective screening. (See 'Risk Factors for Hearing Loss' above and 'Universal screening' above.)

•United States implementation ‒ All states in the United States have implemented universal newborn hearing screening (UNHS) programs and most states have laws mandating UNHS. Clinicians should be familiar with their state laws. Information for each state is available at the National Center for Hearing Assessment and Management. (See 'Implementation' above.)

•Protocols ‒ The two protocols used for UNHS include:

-One-stage, which utilizes a single screening test (ie, AABR or OAE). (See 'Single stage' above.)

-Two-stage, which utilizes two screening tests or repeats the same test. In the two-stage UNHS, only patients who fail the initial test receive a second screening study, and only patients who fail both tests are referred for audiologic assessment (algorithm 1 and algorithm 2). (See 'Two stage' above.)

•Approach ‒ When UNHS is implemented, we suggest the use of a two-stage UNHS versus the one-stage protocol (Grade 2C). At many birthing centers, OAE is the initial test in healthy term infants because of lower cost and ease of administration, followed by AABR if the OAE is abnormal. For infants admitted to the NICU, we use AABR to screen for hearing loss as they are at risk for AN. (See 'Protocols' above and 'Approach to birth hospitalization screening' above.)

If a one-stage UNHS is utilized in the well-baby nursery, AABR should be used as the screening test versus OAE. (See 'Well-baby nursery' above.)

●Follow-up

•Infants who fail hearing screening test require additional audiologic evaluation by three months of age. (See 'Infants who fail two-stage screening' above.)

•Term infants who failed the initial screen but passed the second screen of a two-stage screening protocol should be monitored by their primary care providers for any suggestion of hearing loss, which includes assessment of developmental milestones, speech, auditory skills, parental concerns, and middle ear status during routine well-child visits. (See 'Term infants who failed initial screen but passed the second' above.)

•Infants who pass UNHS but have additional risk factors for hearing loss including >5 day admission in a NICU (table 3) are at risk for late-onset hearing loss. In addition, although UNHS has improved the early recognition of hearing loss, there are still infants with hearing loss not detected by UNHS. To detect hearing loss, routine monitoring includes assessment of language acquisition, auditory skills, and middle ear status, and attention to parental concern. (See 'Infants who pass initial screening' above.)

In addition to routine monitoring for hearing loss, we suggest that these infants be assessed by audiologic assessment by 9 months of age (Grade 2C).

ACKNOWLEDGMENTS — The UpToDate editorial staff acknowledges Lisa M Adcock, MD, and Drifa Freysdottir, MD, who contributed to an earlier version of this topic review.