Kernicterus and Untreated Jaundice

Bilirubin is produced when red blood cells break down. Newborns produce a lot of it — they have more red cells, those cells are shorter-lived, and a newborn liver is still ramping up the enzyme that clears it.

The result is that most healthy newborns become visibly jaundiced in the first days of life, and for most of them it resolves without any intervention. This is the reason the condition is dangerous: the ordinary case and the dangerous case look the same at the start, and both look like a yellow baby.

Certain circumstances accelerate it — blood group incompatibility between mother and infant, bruising from a difficult delivery, prematurity, feeding difficulty and dehydration, G6PD deficiency, infection. Several of those are known before the infant leaves the delivery room, which is why risk assessment before discharge is part of the guidance rather than an optional extra.

At high enough levels, unbound bilirubin crosses into the brain, with a particular affinity for the basal ganglia and brainstem nuclei. That is kernicterus, and it does not reverse.

The single most important thing for a family to understand is that there is no one number.

A bilirubin level that is entirely unremarkable at 72 hours of age can be an emergency at 24 hours, because the level is rising and the infant has days of rising ahead. The guidance therefore plots the measurement against age in hours, not age in days, and reads the threshold off a curve that also accounts for gestational age and for whether neurotoxicity risk factors are present.

This is why "the bilirubin was 15 and nobody was worried" is not a sentence that means anything on its own, and why a clinician recording a level without recording the hour is recording half a fact.

It is also why visual assessment is not sufficient. Estimating bilirubin by looking at an infant is unreliable, particularly in infants with darker skin, and the guidance is built on measurement — by blood or by transcutaneous device — rather than on inspection.

The AAP's revised guideline, published in August 2022, replaced guidance that had stood since 2004. It applies to infants born at 35 weeks' gestation or more.

The most-discussed change was that it raised the phototherapy thresholds modestly, on the reasoning that the previous levels led to substantial overtreatment. Published analyses since have found the revised criteria reduce phototherapy use considerably compared with the 2004 thresholds.

That direction of travel is worth noting honestly in any case that spans the change, because it cuts against a plaintiff on the treatment-threshold question: a level that would have triggered phototherapy under the old guidance may not under the new.

What the revision did not relax is the surrounding structure — universal screening, risk assessment before discharge, and defined follow-up timing after discharge. Those are where the failures in a kernicterus case almost always sit, and the 2022 guideline reinforced rather than loosened them.

Newborn bilirubin typically peaks between three and five days of age. Healthy newborns are frequently discharged at one to two days.

The peak therefore happens at home, which is the structural problem the entire follow-up system exists to solve. The guidance addresses it by requiring a risk assessment before discharge and by specifying when the infant must be seen again — timing that depends on the pre-discharge measurement and the risk factors, not on a fixed interval.

A great many kernicterus cases live in this gap. The infant is discharged without a documented risk assessment, or with one that was performed but not acted on. Follow-up is scheduled for a week later when the guidance called for 24 or 48 hours. The appointment is not kept and nobody follows up on the non-attendance. Or the parents call, describe a sleepy baby who is feeding poorly, and are reassured over the phone.

Each of those is a documented event or a documented absence.

Because the pathway is so well defined, the examinable questions are unusually concrete. In practice they are:

Was a level measured before discharge, and was it plotted? A number recorded in the chart without an hour, or without being compared against the threshold for that hour, is a measurement that was taken but not used.

Was a risk assessment done? Blood group incompatibility, significant bruising, prematurity at 35 to 37 weeks, exclusive breastfeeding with poor intake — these are identifiable before discharge.

Was follow-up scheduled at the interval the guidance specifies, and did it happen? Scheduling is one fact; occurrence is another.

When a parent called, what was recorded? Poor feeding, lethargy, a high-pitched cry and arching are described in the guidance as signs of acute bilirubin encephalopathy, and a triage note recording those alongside advice to attend in the morning is a document that speaks for itself.

When the level was finally found to be high, what happened? Intensive phototherapy and, above defined levels, exchange transfusion are time-critical.

Chronic bilirubin encephalopathy has a characteristic presentation: a dyskinetic movement disorder, hearing loss of a particular type, impairment of upward gaze, and dental enamel defects. Cognition is frequently far better preserved than motor function, which is a distinguishing feature and one that matters enormously to how a life care plan is built.

That last point deserves emphasis because it is routinely missed. A child with kernicterus may have severe physical impairment alongside intact intelligence, which means the claim has to fund communication technology, educational support and the assumption of a normal cognitive life — not merely custodial care.

The claim is otherwise built as other catastrophic birth injury claims are: a life care plan, an economic analysis reducing it to present value, and the lien and benefits work that decides what a settlement is actually worth to the family.