It is understandable for parents of a newborn baby to feel concerned if their baby develops jaundice. However, newborn jaundice is a common condition and, in most cases, it is temporary and easily treated or doesn’t require treatment. In rare cases, if severe jaundice is not recognised or managed properly, it can progress to kernicterus - a serious complication that can cause permanent brain damage. By understanding what kernicterus is, how it develops and the treatment available, parents can feel more informed about the condition and its potential impact.

Eddie Jones of JMW’s medical negligence team explains what causes kernicterus in newborn babies, the risks if it is left untreated, and how families affected by kernicterus can access the support they need.

What Is Acute Bilirubin Encephalopathy?

Acute bilirubin encephalopathy is a term often used to describe the early stages of kernicterus, a serious and preventable condition linked to severe newborn jaundice. Jaundice occurs when too much bilirubin, a yellow substance produced as red blood cells break down, builds up in the baby's blood. Normally, the liver filters out bilirubin so it can leave the body, but in some newborn babies - particularly those born prematurely or who are not feeding well - the liver may not yet be developed enough to process the unconjugated bilirubin.

When total serum bilirubin levels rise too high in the baby's blood, they can overwhelm their body’s natural defences and cross the blood-brain barrier. At this stage, the condition is referred to as acute bilirubin encephalopathy. If jaundice and elevated bilirubin levels are not recognised and treated quickly, the bilirubin can damage parts of the brain responsible for hearing, movement, learning, and vision. This damage is permanent and is known as kernicterus.

If jaundice occurs, early diagnosis and, where necessary, treatment is vital to stop bilirubin from reaching dangerous levels and to safeguard a baby’s long-term health. Parents and healthcare professionals should be alert to the early signs of neonatal jaundice, which may result in:

• Poor feeding: difficulty latching or refusing feeds.
• Irritability: being unsettled and hard to comfort.
• A high-pitched cry: sounding different to a baby’s usual cry.
• No startle reflex: a loss of the baby’s natural reflex movements.
• Lethargy (sleepiness): being unusually drowsy or difficult to wake.
• Brief pauses in breathing (apnoea): short episodes where breathing stops.
• Weak muscles: the baby may appear floppy or lack normal muscle tone.

What Causes Neonatal Jaundice and Kernicterus?

Jaundice is common in newborns, and while it is often mild and temporary, it can cause serious complications if not recognised or managed properly. Factors that can contribute include:

• Bilirubin toxicity: when bilirubin builds up to very high levels, it can overwhelm the body’s ability to remove it. If not treated, the bilirubin can pass into the brain and cause permanent damage.
• Delayed diagnosis: jaundice usually appears in the first days after birth, with yellowing of the skin and eyes being the most obvious sign. If these early symptoms are missed, or elevated bilirubin levels haven't been treated, kernicterus can continue to develop unchecked.
• Failure to monitor: once jaundice has been detected, babies need close observation, often with repeated blood tests to track bilirubin levels. Without proper monitoring, the severity of the condition may not be identified in time for treatment to be effective.
• Inadequate treatment: many cases of jaundice can be treated with light or phototherapy, which is often performed in a neonatal intensive care unit. During phototherapy, a special blue light helps break down bilirubin in the baby's skin. However, in more severe cases, an exchange transfusion may be needed. This procedure replaces the baby’s blood with donor blood to rapidly reduce bilirubin. If treatment is delayed or not escalated appropriately, the risk of kernicterus increases.
• Birth injuries: bruising or internal bleeding during a difficult delivery can increase the breakdown of red blood cells in a baby's body. This releases increased levels of bilirubin into the bloodstream, making jaundice more likely and more severe.
• Premature birth: babies born before 37 weeks of pregnancy are more vulnerable to jaundice because their liver is not fully developed and may struggle to process bilirubin effectively.
• Blood type incompatibility: when the mother and baby have different blood groups, such as Rh or ABO incompatibility, the mother’s antibodies can attack the baby’s red blood cells. This causes the cells to break down more quickly than normal, leading to dangerously high bilirubin levels in the baby’s blood.
• G6PD deficiency: a genetic condition that affects the red blood cells. This happens when there is a mutation in the gene that your body needs to make enough glucose-6-phosphate dehydrogenase. Diagnosis is done via blood tests or genetic testing.

While many babies experience jaundice in the early days of life, it is usually treatable when recognised promptly. If doctors or nurses fail to diagnose or manage newborn jaundice, this could be classed as medical negligence.

What Are the Risks if Jaundice Isn't Treated Early?

If severe jaundice is not treated in time, it can progress to chronic bilirubin encephalopathy, where excess bilirubin causes permanent brain damage for the baby. This type of brain injury is sometimes referred to as bilirubin-induced neurologic dysfunction (BIND) and can have a profound impact on a child’s development and quality of life.

The long-term effects of untreated jaundice may include conditions affecting the central nervous system such as cerebral palsy, which affects movement and coordination, hearing loss ranging from mild to profound, and developmental disabilities that can make learning and daily activities more difficult. Babies may also develop problems with their vision, including visual impairments or difficulty controlling eye movements, often known as upward gaze palsy.

Other complications can involve physical development, such as poor growth of the teeth, and severe problems with muscle control. These can include involuntary twitching or jerking, as well as unusual postures such as arching of the spine. Because the damage caused by kernicterus is permanent, preventing it through early diagnosis and treatment of jaundice is essential for protecting a child’s long-term health.