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LESSON 175

After a refer result

Year 2
Spring semester
Hearing Screening
Screening programs
Duration: 10:59

When and with which tests is a baby who did not pass newborn screening evaluated? In this lesson we cover referral to a diagnostic center, the diagnostic test battery, the possible outcomes and ways to reduce loss to follow-up.

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Hello, and welcome to the AIHEAR Audiology Academy.
In this lesson we will learn how a baby who did not pass screening is referred for diagnosis and what the diagnostic evaluation includes.
Then we will look at loss to follow-up, one of the biggest problems of screening programs, and ways to reduce it.
For a baby who also did not pass rescreening, the first step is to explain the result to the family clearly and calmly.
It is stressed both that a refer result is not a diagnosis and that further evaluation is necessary and urgent.
If possible, the diagnostic appointment is given in writing before the family leaves the hospital.
The baby is referred to an audiology unit with the experience and equipment for pediatric evaluation.
The aim of the diagnostic evaluation is to determine, for each ear and by frequency, whether there is a loss, and its type and degree.
According to the Joint Committee on Infant Hearing, diagnosis should be made by 3 months under 1-3-6, and by 2 months under 1-2-3.
The result is reported in writing to the family and the baby's physician, and the tracking system is updated.
In the first months, a diagnostic auditory brainstem response, or ABR, can often be done in natural sleep, without medication.
In a young baby who falls asleep right after feeding, getting a long, clean recording is relatively easy.
As the baby grows this gets harder, and after about six months sedation may be needed; the sedation decision belongs to the physician.
For a congenital cytomegalovirus, or CMV, test to be meaningful, the sample must be taken within the first three weeks of life.
So the medical evaluation of a baby who did not pass screening is also planned without delay.
Most importantly, a delayed diagnosis also delays hearing aid fitting and early intervention.
So the diagnostic appointment is set with these time windows in mind, as well as the family's availability.
The diagnostic evaluation is not a single test but a battery of tests that cross-check each other.
It starts with a detailed history, questions about risk indicators and family history, and otoscopy.
At the center of the battery is frequency-specific ABR, used to estimate thresholds.
If an air conduction loss is found, bone conduction ABR helps to tell the type of loss.
Click ABR at a high level in two polarities is used to assess the cochlear microphonic and signs of auditory neuropathy.
Otoacoustic emissions, or OAE, give information about outer hair cell function and are interpreted together with ABR.
Tympanometry with a 1000 hertz probe tone shows the status of the middle ear.
Acoustic reflex measurement is complementary information that can be added to the battery.
Frequency-specific ABR, the basis of diagnosis, uses brief tonal stimuli, or tone bursts, instead of clicks.
This allows separate threshold estimates for 500, 1000, 2000 and 4000 Hz.
At each frequency, the level is lowered to find the lowest level at which wave V can still be seen.
Thresholds found in normalized hearing level, or nHL, are converted to estimated hearing level, or eHL, with frequency-specific corrections.
To get the most information before the baby wakes, 2000 Hz can be tested first in each ear, then 500 Hz.
This information is also the basis for later hearing aid fitting; prescriptive formulas are calculated from these thresholds.
We saw the method in detail in the threshold ABR lesson; here we focus on its place in the diagnostic process.
In some babies who did not pass screening, the cause of the problem is fluid in the middle ear.
In babies younger than six months, a 226 hertz probe tone can give a normal-looking curve even in an ear with fluid.
So in this age group, tympanometry is done with a 1000 hertz probe tone.
A finding of middle ear fluid can explain absent OAEs and elevated air conduction thresholds on ABR.
But there may also be a sensorineural loss beneath the fluid, so bone conduction ABR and monitoring are important.
A baby with signs of fluid is referred for medical evaluation and retested after the fluid clears.
At the end of the diagnostic evaluation, we may meet one of four possible pictures.
The first is normal hearing; the family is told to watch development, and about planned monitoring if there is a risk.
The second is a temporary conductive loss due to middle ear fluid.
These babies are re-evaluated after the fluid clears; if the problem persists, permanent loss is investigated separately.
The third is a permanent loss; this is usually sensorineural, and sometimes a permanent conductive loss from an outer ear anomaly.
The fourth is auditory neuropathy spectrum disorder, or ANSD, with OAE or cochlear microphonic present but ABR absent or abnormal.
A baby found to have permanent loss or ANSD is referred without delay for medical evaluation and early intervention.
Loss to follow-up is when a baby who did not pass screening never reaches diagnostic evaluation.
If the evaluation was done but the result was not reported to the program, this is called loss to documentation.
From the program's point of view, both lead to the same outcome: the baby's status is unknown.
In 2020 data from the US CDC, about 30 percent of babies who did not pass screening were lost to follow-up or documentation.
Although this rate has fallen over the years, it shows how important loss to follow-up is, even in a well-developed program.
Loss to follow-up means that the diagnosis of a baby with permanent loss is delayed by months, or even years.
When diagnosis is delayed, fitting and early intervention are delayed too, and the purpose of screening is lost.
The first cause is that the family blames the refer result on something temporary, like vernix or noise, and dismisses it.
Practical barriers such as a distant diagnostic center, travel and lost workdays also matter.
A missing or wrong phone number in the hospital record can mean the family is never reached.
Long waiting times at diagnostic centers push the appointment beyond the time targets.
Even if the evaluation is done, the baby looks lost if the result is not entered into the central tracking system.
Finally, if information was not given in a language the family understands, they may not see why the appointment matters.
Most of these causes can be prevented through the program's own processes.
The first and most effective step is to give the diagnostic appointment before the family leaves the hospital.
At least two sets of family contact details are recorded, and a reminder is sent before the appointment.
A family who misses the appointment is called and given a new one; one named person is responsible for this step.
What a refer result means is explained in a language the family understands, both spoken and in writing.
The result is also sent to the baby's family physician, so the appointment is checked at well-child visits.
A central tracking system makes it possible to follow every baby from screening to diagnosis and intervention.
These steps make it possible to measure a program's success by its follow-up rate as well as its screening rate.
A tip from the field: downplaying a refer result so as not to scare the family is one of the most common causes of loss to follow-up.
Phrases like "there is probably nothing wrong" can lead the family to postpone the appointment.
Instead, say that the result is not a diagnosis, but that diagnostic testing is the only way to know for sure about hearing.
Give the date and place of the appointment in writing, and show the family whom to call if they have questions.
For every baby who misses an appointment, the record should state what the next step is.
In this lesson we saw that a baby who did not pass screening should be diagnosed by 3 months, or by 2 months under the newer goal.
The diagnostic battery includes history, frequency-specific ABR, click ABR, OAE, 1000 hertz tympanometry and acoustic reflexes.
The outcome may be normal hearing, temporary conductive loss, permanent loss or ANSD.
Loss to follow-up is one of the biggest problems of programs and can be reduced through appointments, contact and tracking systems.
Test yourself: which of the following reduces loss to follow-up the most?
The correct answer is B: booking the appointment before discharge.
An appointment given before the family leaves the hospital, and handed over in writing, is one of the most effective steps.
In the next lesson we move from the newborn period to school age and look at school hearing screening.
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Prerequisites

LESSON 174 Risk indicators and monitoring

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