In many cases, kernicterus can be prevented when doctors and midwives recognise severe newborn jaundice, measure bilirubin levels correctly and provide treatment before bilirubin causes permanent brain damage.

Most newborn or infant jaundice is mild and does not cause lasting harm. However, untreated jaundice can become dangerous if too much bilirubin builds up in a baby's blood. The bilirubin can enter the brain and cause acute bilirubin encephalopathy. If the injury becomes permanent, this is known as kernicterus.

Timely medical intervention is therefore vital. Depending on the baby's bilirubin levels, postnatal age and gestational age, treatment may involve close monitoring, phototherapy or, in severe cases, an exchange transfusion. NICE (the National Institute for Health and Care Excellence) provides treatment thresholds that doctors and neonatal teams should use when deciding what action is required. Read the NICE guidance on jaundice in newborn babies.

Where a child developed kernicterus after opportunities to test, monitor or treat severe jaundice were missed, it may be appropriate to investigate whether medical negligence caused or contributed to their brain injury. You can also read our broader guide to what kernicterus is.

At a glance: how can kernicterus be prevented?

Preventing kernicterus depends on identifying and treating dangerous bilirubin levels before permanent brain damage occurs. Important steps can include:

• Recognising jaundice and taking parents' concerns seriously
• Measuring bilirubin rather than relying on the baby's appearance alone
• Considering the baby's age, gestational age and other risk factors
• Repeating bilirubin checks when clinically required
• Starting phototherapy when the relevant treatment threshold is reached
• Escalating to intensified phototherapy or an exchange transfusion where necessary
• Supporting feeding while continuing to monitor the baby's condition

NICE guidelines state that jaundice appearing during the first 24 hours of life requires particularly urgent assessment.

How does jaundice develop into kernicterus?

Kernicterus occurs when high levels of unconjugated bilirubin enters brain tissue to cause permanent neurological damage. Before this happens, bilirubin toxicity can cause acute bilirubin encephalopathy.

Kernicterus can affect children differently depending on the extent and location of the brain injury. A kernicterus diagnosis may be associated with problems involving movement, hearing, muscle control and development.

Where medical errors in bilirubin testing, monitoring or treatment cause avoidable delays, it may be appropriate to investigate whether medical negligence contributed to the brain injury.

Why does early intervention make such a difference?

There can be an opportunity to treat dangerously high bilirubin before permanent kernicterus brain damage develops.

This is why early diagnosis and treatment are important. Lowering bilirubin while the condition is still treatable can prevent further bilirubin from entering the brain and reduce the risk of permanent injury.

Once kernicterus has developed, however, the brain damage itself is permanent. Treatment of neonatal jaundice is therefore focused on preventing severe hyperbilirubinaemia from progressing to this stage.

How should doctors and midwives monitor jaundice?

Doctors and midwives should assess newborn babies for jaundice and arrange bilirubin testing where required.

For babies with suspected or obvious jaundice during the first 24 hours after birth, NICE guidelines recommend measuring the serum bilirubin level urgently, within two hours. Measurements should then continue at appropriate intervals until the level falls below the treatment threshold and is stable or falling.

For babies more than 24 hours old with suspected or obvious jaundice, the guidelines recommend measuring and recording the bilirubin level urgently, within six hours.

Depending on the baby's postnatal age and gestational age, the neonatal team may use a transcutaneous bilirubinometer, sometimes described as a light meter, to estimate bilirubin through the baby's skin.

A total serum bilirubin blood test is required in particular circumstances, including for babies who develop jaundice within their first 24 hours, babies born before 35 weeks, and where the bilirubin result reaches levels that require confirmation or treatment.

How do doctors decide whether treatment is needed?

There is no single bilirubin level or measurement that determines whether or not treatment is mandated for every newborn baby.

Doctors and neonatal teams should formulate a treatment plan after considering the levels of serum bilirubin in conjunction with a number of factors including:

• How much bilirubin is present
• The baby's postnatal age in hours
• The baby's gestational age

NICE provides standardised treatment threshold tables and graphs for this purpose. The bilirubin level requiring treatment can differ depending on how premature or how young a baby is.

Doctors therefore need to use the correct treatment chart and respond to the individual baby's circumstances rather than looking at the bilirubin figure in isolation.

Our guide to the risk factors for kernicterus provides more information about factors that may make closer assessment or monitoring particularly important.

How does phototherapy help prevent kernicterus?

Phototherapy, or light therapy, is the main treatment used when bilirubin rises above the relevant treatment threshold.

The baby is exposed to a specific type of artificial light that changes bilirubin into forms the body can remove more easily. Phototherapy can therefore lower bilirubin before it reaches a level where the brain is at risk.

During phototherapy, doctors should continue to monitor serum bilirubin. NICE recommends checking it four to six hours after phototherapy begins, followed by further measurements every 6 to 12 hours once the level is stable or falling.

If bilirubin continues to rise quickly, approaches the exchange transfusion threshold, or does not respond adequately to initial treatment, intensified phototherapy may be needed.

When is an exchange transfusion needed?

An exchange transfusion may be required in severe cases when bilirubin reaches the relevant threshold or the baby develops clinical signs of acute bilirubin encephalopathy.

During the procedure, some of the baby's blood is progressively replaced with donor blood. This rapidly reduces the amount of bilirubin circulating in the baby's blood and can reduce the risk of further brain injury.

NICE recommends a double-volume exchange transfusion where the serum bilirubin level indicates that it is necessary and/or the baby has signs of acute bilirubin encephalopathy. Continuous intensified phototherapy should continue during the procedure.

An exchange transfusion is reserved for severe cases, but it can be a crucial emergency intervention where bilirubin has reached dangerous levels.

Which babies may need closer monitoring?

Some newborn babies have risk factors that make significant jaundice more likely or mean doctors and midwives need to pay particularly close attention to rising bilirubin.

Relevant factors can include premature birth, jaundice appearing during the first 24 hours, blood group incompatibility or haemolytic disease, and certain conditions affecting red blood cells, including G6PD deficiency. Feeding difficulties may also contribute to concerns about how effectively bilirubin is being removed from the baby's body.

The significance of individual risk factors varies. What matters is that the doctor, midwife or neonatal team recognises the baby's circumstances, arranges appropriate bilirubin checks and responds promptly if the results show that treatment is needed.

Read our guide to the risk factors for kernicterus for more information.

What are the early signs that bilirubin may be affecting the brain?

A baby with severe jaundice or acute bilirubin encephalopathy may develop symptoms including:

• Unusual sleepiness or difficulty waking
• Poor feeding or refusing feeds
• A high-pitched cry
• Unusual floppiness
• Muscle stiffness
• Jerking, twitching or seizures
• Unusual movements or changes in behaviour

The NHS advises parents to seek urgent medical advice when a baby with jaundice develops concerning symptoms such as being difficult to wake, becoming reluctant to feed or showing other signs of being unwell. Read the NHS guidance on jaundice in babies.

These symptoms in isolation do not necessarily confirm a diagnosis of kernicterus, but they do mean that an urgent medical assessment is indicated. 

Our guide to the key symptoms of kernicterus explains the warning signs and how they can progress.

Can kernicterus be reversed?

Established kernicterus cannot be reversed because it describes permanent brain damage caused by bilirubin toxicity.

However, acute bilirubin encephalopathy occurs before the condition has necessarily progressed to permanent kernicterus. Rapid treatment aimed at lowering bilirubin may prevent or limit permanent damage if doctors intervene early enough.

This distinction is important. Phototherapy and exchange transfusion treat the dangerously high bilirubin levels that can cause kernicterus; they do not reverse brain damage once it has become permanent.

What is the prognosis for a child with kernicterus?

The effects of kernicterus depend on the extent and location of the brain injury.

Long-term complications can include:

• Cerebral palsy and other movement disorders
• Hearing loss
• Difficulties with balance and coordination
• Abnormal muscle tone or involuntary movements
• Feeding or swallowing difficulties
• Speech and communication problems
• Vision problems or abnormal eye movements
• Developmental difficulties

Kernicterus can therefore affect many aspects of a child's life and, in severe cases, create substantial lifelong care and support needs. Families may be trying to understand not only why the injury happened, but also what their child's future care, therapy, education and equipment needs may look like.

For more information about one of the potential long-term consequences, read our guide to how kernicterus can cause cerebral palsy.

When could a failure to prevent kernicterus amount to medical negligence?

A child diagnosed with kernicterus does not automatically mean that medical negligence has occurred. We need to investigate the individual circumstances and the care provided.

Questions about the standard of care may arise where a doctor, midwife or nurse failed to recognise or properly manage severe jaundice. Examples can include:

• Failing to respond appropriately when parents report jaundice or changes in their baby's feeding or behaviour
• Relying on visual inspection without arranging appropriate bilirubin testing
• Delaying a serum bilirubin test
• Failing to monitor rising bilirubin levels
• Using the wrong treatment threshold for the baby's age or gestational age
• Delaying phototherapy when the treatment threshold had been reached
• Failing to escalate treatment when bilirubin continued to rise
• Delaying an exchange transfusion when one was clinically indicated

JMW has supported families in cases where failures to recognise and treat severe jaundice led to kernicterus.

CP developed kernicterus brain damage after his jaundice was not treated appropriately, leaving him with severe sight impairment and unable to stand or walk. His family approached JMW, and the hospital trust later admitted negligence. Read CP’s story to learn more about what happened and how the claim helped to secure provision for his long-term care, accommodation and specialist equipment. 

A medical negligence investigation considers two important questions: whether the care fell below a reasonable standard and whether timely, appropriate care would probably have prevented or reduced the child's brain injury.